Wifi and the router: the basic ideas
A modem translates the operator line into something the devices at home understand, and a router decides which device each packet goes to; in most Iranian homes both sit inside one box and we call the whole thing the modem. Wifi is neither the internet nor the network, only one of the two ways to reach that router, the other one being a cable.
- Lesson 10 of 12
- Beginner
- Free, no signup
Six jobs that box in the corner is doing
- The operator line
- The cable ports
- The wifi radio
- The guest network
- Firewall and address translation
- The admin panel
In most Iranian homes the modem half is inside this same box too, which makes seven. The split is here to be understood; on your device it is all one menu.
Last checked: Facts and tool names in this lesson are re-checked against their sources on this date.
A modem and a router are not the same thing. What is the difference?
Two entirely different jobs that have been put inside one box for years. A modem is a translator: the signal arriving on the phone line or the fibre or the mobile antenna speaks one language and the devices in your home speak another, and the modem translates between them. On fibre it is usually called an ONT, doing the same job with light instead of electricity.
A router is a traffic officer: it gives every device at home a local address, decides which device each packet goes to, and takes all of them out to the world behind one public address. The firewall and the guest network are jobs of this same half.
Why does the split matter? Because when someone tells you to replace the modem, it is usually the router half that has run out of capacity, not the modem half. The sign is clear enough: if one device on a cable straight into that box is fast and steady while everything else limps, the line is healthy and the problem is in the distribution. The cheaper answer then is to buy a separate router and switch off the wireless half of the operator box, not to change the whole service.
One thing that surprises many people: switching off the wifi does not cut the internet. Devices on a cable keep working exactly as they were, because wifi is only the radio layer of that same network.
2.4 or 5 GHz? Choosing between reach and speed
One simple piece of physics sits behind this choice: a wave at a lower frequency travels further and passes through walls better, and a wave at a higher frequency carries more data. So 2.4 GHz has reach and 5 GHz has speed, and neither is better.
The practical translation: anything in the same room as the router or near it should go on 5, and anything at the far end of the home behind two walls should stay on 2.4. A television, a console and a laptop doing work belong on 5; a thermostat, a smart bulb and a camera in the yard almost always know only 2.4 and have no choice anyway.
The question that always comes up: should both bands share one name or have separate ones? The honest answer is that it depends, and we have seen both work. One name is easier and the device chooses for itself, but when a phone clings to 2.4 and will not let go there is nothing you can do about it. Two separate names are uglier and hand the control to you. If the home is large and you are having trouble, split them; if everything works, leave it alone.
There is a third band too, 6 GHz, which arrived with Wi-Fi 6E and 7. We pass over it briefly on purpose: devices on sale in Iran still support it thinly, and recommending something your phone does not know is of no use.
Two bands, two different jobs
2.4 GHz
- Travels further and passes through walls better
- Its channels overlap and there is less room
- The most crowded band in any apartment block
- The only option most smart home devices have
- For the far room, the yard and low traffic devices
5 GHz
- Carries more data
- Has less reach and a wall weakens it more seriously
- Has more channels, so it is usually less crowded
- Very old devices cannot see it at all
- For the same room: television, console, video meetings
This split is for an ordinary home. In a building where dozens of networks overlap, channel congestion outweighs every line in this table.
Why does a neighbour wifi affect yours?
Because air is not a cable. A cable shares its capacity with nobody, but every wireless device in a building sitting on the same frequency is in practice using one shared room and has to take turns. While one is talking, the rest are silent.
That turn taking has a name and it is the least understood thing in this topic: airtime. An old, distant device that talks slowly occupies the air for longer to send the same amount of data, and so slows every other device down. This is why an old laptop at the far end of the home sometimes drags down the speed of a phone sitting right beside the router.
The 2.4 GHz band has a second problem: its channels overlap, and in an ordinary apartment block dozens of networks sit on the same few channels. The 5 GHz band has more room, and that alone is reason enough to move whatever you can onto 5. Changing the channel by hand sometimes helps, but do not expect a miracle; in a building where everyone is crowded, the best channel is crowded too.
What actually works, and nobody likes hearing it: reduce the distance. A router in the middle of the home and up off the floor beats any setting, and running cable to the stationary devices also clears the air for everything else.
What does the number written on the router box mean?
They print one big number on the box and that number is almost never what a single device of yours gets. It is the sum of the theoretical rates of every radio in the unit: the 2.4 band rate plus the 5 band rate. No phone or laptop connects on both bands at once, so that total is unreachable for any one device from the start.
Each band figure on its own is a theoretical rate too, under the best laboratory conditions with full signal. What arrives in practice is less, because part of the time goes on taking turns and acknowledging, and distance and walls take their own share.
Now the point that changes a purchase: this number is the ceiling of the radio inside your home and has nothing to do with the speed of your internet line. If your line is slower than the router radio, buying a router with a bigger number makes nothing faster. To work out where the real limit sits, go to the internet and networking lessons; bandwidth and latency are separated there with measurements.
So when is a more expensive router worth it? When there are many devices or the home is large. In practice that money buys a better antenna, a processor that does not buckle under thirty devices, and better handling of the shared air, not the number on the box.
Which router setting actually buys you security?
Four things are worth doing and all of them once. Change the admin panel password, which is not the wifi password. Switch off remote management if it is on. Set the encryption to WPA3, or WPA2 where a device cannot handle WPA3; the Wi-Fi Alliance itself presents WPA3 as the current generation. And turn WPS off.
Let us pause on WPS, because few people know the reason. That convenient button on the router also has an eight digit PIN, and in 2011 the CERT coordination centre in the United States announced that the design of that PIN lets an attacker guess it in pieces, so the number of combinations that must be tried collapses. That is a design weakness, not a weak password; changing the wifi password does not fix it and the only remedy is switching the feature off.
Now two things everyone recommends that are not security: hiding the network name and filtering devices by their hardware address. A hidden network name is audible in the air as soon as your own devices go looking for it, and a hardware address is never encrypted and changing it is a simple setting on any laptop. Those two are an inconvenience, not a protection, and their worst effect is giving you a feeling of safety that does not exist. What actually protects your traffic is the encryption, and nothing else.
And one thing that comes up often in Iran and should be said plainly: on many fibre modems the administrator account password belongs to the operator and you have no access to that account. In that case this list is followed as far as the user panel allows and the rest has to be asked of the operator. Pretending everything is in your hands does not help.
What buys security and what only buys the feeling of it
Read the second column carefully. All four of its lines are recommended in every Persian guide you will find.
Actually works
- Change the admin panel password (not the wifi one)
- Switch off remote management
- Set the encryption to WPA3, otherwise WPA2
- Turn WPS off; its weakness is in the PIN design
- Update the firmware and put guests on the guest network
Only gives the feeling
- Hiding the network name; your own devices give it away
- Hardware address filtering; it is unencrypted and changeable
- Lowering the antenna power hoping it will not reach outside
- Changing the channel as if it were a security setting
If the administrator account on a fibre modem belongs to the operator, follow the first column as far as the user panel allows and ask the operator for the rest.
The fast path, with AI
The ordinary way to secure a router is to open a guide and do everything it says, including the two or three items that achieve nothing. The fast way is to take a short inventory off your own device first and then force the language model to rank only that inventory. The difference is that in ten minutes you learn which three settings are worth it on this particular device and you drop the rest.
- Take the exact device model and the firmware version from the label on the box and from the first page of the panel. Not from the operator invoice; similar names are common.
- Open the panel and note just five things: whether the panel password was changed, whether remote management is on, whether WPS is on, what the encryption type is, and whether you have a guest network. Change nothing yet.
- Hand the inventory to a frontier class model and ask it to order only those items by real risk for a home and to say exactly what each one exposes.
- Match the location of each setting against the manufacturer own manual and change one at a time. If a device drops after one change, you know which change it was.
Copy-ready recipe
You are a home network security specialist. Judge only from the list below and add no setting to it.
Device model (from the label): {model}
Firmware version: {version}
Current state, as I saw it in the panel:
- Admin panel password: {changed / still the factory value / I do not know}
- Remote management: {on / off / could not find it}
- WPS: {on / off / could not find it}
- Wifi encryption type: {WPA3 / WPA2 / WPA / WEP / open}
- Guest network: {have it and use it / have it and it is off / do not have it}
Write three things:
1. Order these items by real risk for a home, highest to lowest, and write one sentence for each saying exactly what it exposes.
2. Which three should I change first, and in what order.
3. For any item I marked as could not find it, write which phrase to look for in the manual for this model.
Rules: do not write the menu path of this device from memory; if you are unsure, say to check the manual. Do not propose a setting that is not in the list above. And if you think something in the list has no real security effect, say so plainly.Before you trust the output: Do not write the wifi password or the panel password into any prompt; they are not needed to rank risk, and whether it was changed or not is all the model needs to know. And if the answer proposes two particular things, stop right there: hiding the network name and hardware address filtering are repeated so often in online advice that models suggest them too, while neither adds any encryption and both only make your own life harder.
AI in this kind of work
On this topic a language model does two things very well and one thing it should not do at all. Well: explaining concepts with examples, and ordering a list of settings by importance. Badly: telling you exactly where an option lives in your device firmware. The model memory is a blend of thousands of different manuals, and on your particular device it will get the menu path wrong with complete confidence.
Tools that actually help
- Gemini Notebook It has one use here that nothing else has: upload both the router PDF manual and the operator setup guide together and ask where the two documents disagree about a setting. The answer comes from the text of those two documents, and those disagreements are usually exactly the places where support and the manual tell you two different things. It runs on a Google account, and Iran is not among the available regions.
- Claude For handing over a list of the networks around you with their channels and getting an analysis of the crowding, and for ranking the same five items you collected in the fast path. Iran is not on Anthropic list of supported countries, so there is no official route to sign up or pay.
- Gemini For translating the English terms in a router panel into Persian, which on most devices are not translated at all. Google own page says the Gemini app works in more than 230 countries and territories, and Iran is not on that list.
Where it backfires
The specific risk in this topic is that models reproduce the common mistakes of the internet, because they learned from those same texts. Hiding the network name and hardware address filtering are recommended as security in thousands of guides, and the model suggests them in the same tone; neither adds any encryption. The second risk is the menu path: the model names a path with complete confidence that does not exist in your device firmware, and Anthropic itself calls this confident invention hallucination in its documentation and writes about reducing it, which means the vendor treats it as a real weakness. And the third and most serious: any answer that proposes opening a port, putting a device into DMZ mode or switching off the firewall in order to solve a problem is removing the same default protection. On data, Google own help page for Gemini says plainly not to enter confidential information, and a router panel password is exactly that. For what paying for these tools looks like from Iran, see the buying guide.
Sources: CERT VU#723755: WiFi Protected Setup (WPS) PIN brute force vulnerability Wi-Fi Alliance: security Anthropic: reduce hallucinations Anthropic: supported countries Google: Gemini Apps privacy and data Google: where Gemini Apps are available
Where this advice stops
This lesson explains a home router or a small office. Mesh systems with several access points, business equipment with virtual networks that separate traffic and per user logins instead of one shared password, and covering a building of several floors, all start with these concepts and do not end with them. Two more boundaries stated plainly. First, none of these settings makes a slow operator line fast; if the problem is outside the home, the best router in the world changes nothing. Second, on fibre modems where the administrator account belongs to the operator, part of this list is genuinely not yours to change, and the route is to obtain access or replace the device, not to work around it.
From our own work
That default password lists really are tried is not our guess; it shows in our own server login log. We deliberately moved this machine login service off its default port and that removed almost all of the automated noise; even so, between 30 August and 7 September 2026 the log recorded 84 failed login attempts from only 9 addresses, and 34 of them used a username that does not exist on this server at all. The most interesting part is the list of names itself: beside admin, ftp and tomcat, the name telecomadmin was tried twice. That name means nothing on a web server and means something only on fibre modems, which tells you the scanner that reached us throws the same list at the modem in your home. And compare that with our own site behind its security layer: over the same window only three lockouts were recorded. The distance between 84 and 3 is the size of what one simple setting does.
Real follow-up questions
Should the 2.4 and 5 networks share one name or have separate ones?
If everything works, use one name and leave it alone; it is easier and the device chooses for itself. Splitting them is worth it when one particular device is stuck on the wrong band and will not let go, because then you can attach it to the right band by hand. The cost is that you have to switch networks yourself as you move around the home.
Does hiding the network name add security?
No. A hidden name disappears from the public list of networks but not from the air; your own devices looking for it send the name out and anyone listening hears it. In practice it only makes connecting your own devices harder. What actually protects you is WPA3 or WPA2 encryption with a long password.
How many devices can connect to one wifi at the same time?
The number in the specification is almost never the real limit. The real limit is airtime: the more devices there are and the slower they are, the later each one gets its turn, and quality drops long before you reach that number. If the home is crowded, moving the stationary devices onto cable helps more than buying a new router.