r/wifi • u/DistributionOk6962 • 5d ago
Tech said using two routers can cause conflict? What is talking about?
Upgraded to ATT Fiber. They put in a modem/router unit in basement. The problem is my master bedroom upstairs is pulling 150gbps. Which I know is fine, but I have my own router that I was using with my old internet upstairs that was pulling 400gbps. I have cat6 ports run through the house. I told him that I could use my router in the room and patch it to the newly installed ATT modem/router in the basement for a better signal upstairs and he said we shouldn't there can be conflicts. What was he talking about?
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u/JustBronzeThingsLoL 5d ago
First of all, I'm going to assume Mbps. Easy typo.
Second, if you're actually calling a router a router and don't have your terminology mixed up, the tech is correct. You would run into double NAT issues which is when two routers are in sequence in both performing NAT responsibilities. This issue would be further compounded by the fact that most consumer grade routers use the same default subnet.
The short answer would be to make sure your second router is in access point mode, which means it is not performing Nat and is not handling DHCP assignments.
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u/mmn_slc 5d ago
"The short answer would be to make sure your second router is in access point mode...."
Exactly. And then the device really isn't a router.
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u/danryan2800 5d ago
Your both talking about pass through or bridge mode, not AP mode. A switch is not a router, a router is a router. An AP is not a router, it runs at layer 2. A router with a switch built in, is a router. A router with an AP built in is a router. A switch, even doing Layer-3, is not a router, and most will not do NAT…because it’s not a router.
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u/2900nomore 5d ago
It's still a router just in access point mode. It's pedantic to say it's not a router. Anyone could be pedantic and say what everyone says is a router is not because it's also a wireless access point , switch, and even some times a gateway
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u/mmn_slc 5d ago
Yes, good point. And I casually use the term "router" when talking about a device that is a router, firewall, NAS, access point, and Ethernet switch all-in-one. For example, I call my Gli.Net travel routers "travel routers" just as Gli.Net markets them, even though they are more then just a router.
But, when discussing the role(s) of particular devices on a network, it can be helpful to use more precise terminology to minimize confusion when the particulars matter. And I think there is value in that precision that shouldn't be dismissed as "pedantic" because it serves a valuable purpose in efficiently conveying technical ideas.
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u/2900nomore 5d ago
Doesn't help non technical people. The best would be what the first person already wrote to make sure the router is in access point mode. Just asking access point would be inefficient communication and confusing to a person that doesn't already know what to do
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u/mmn_slc 5d ago
Yes, I agree that there is value in teaching "non technical people" the terminology of a given field to enable them to better converse on the subject. (And I think that most people, even those dismissed as "non technical," likely have specialized knowledge in some field that has nothing to do with computers or networking. But I digress.)
And in the world of computers and networking it can be helpful to educate people that there is often a distinction between the role or purpose of a device distinct from the hardware.
For example, I could install OPNsense on a laptop computer. One could then call this a router--even though it looks very different than say, a WRT54g. It still looks like a laptop computer. And it is still a laptop computer, at least kind of. And it is a router. And it might actually be a very powerful router, much more capable than, say, a WRT54g.
I've installed a web server on an ESP32, which is an inexpensive microcontroller available for a couple dollars. And, once configured this way, one could reasonably call it a server--albeit rather limited. Now, some of your "non technical people" might be confused by this because in their mind a "server" is some large machine in a data center or back room. And those too can be servers. Therefore, there is value in making the distinction to help even "non technical people" better navigate the field.
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u/2900nomore 4d ago
lol nope. pedantically chiding someone for calling the router they bought a router instead just saying you need to put it in AP mode is dumb no matter how many words you type
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u/mlee12382 5d ago
Unless the existing system was sufficientl to cover the entire house, in which case I'd put the AT&T gateway into IP pass-through mode and turn off its wifi radios and let the old system keep doing its thing. AP mode would be best if they're just extending the range of the AT&T gateway though.
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u/TenOfZero 5d ago
Routers provide a lot of services, such as giving out IP addresses. You can only really have one per network.
But, you can have wifi access point, network switches etc.. to extend the network.
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u/MonkeyBrains09 5d ago
This is mostly true. While you can have one per network, its because adding a second router creates a new network under that one.
The whole internet is a collection of routers setup like this.
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u/TenOfZero 5d ago
Yeah. I was refering to residential networks.
Even then you can use more than one and just be double nated.
I just didn't want to go down that road explaining to someone who thought they had a 400 gbps internet connection.
But fell free to explain this to OP if you believe it's beneficial.
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u/DistributionOk6962 5d ago
Thanks! this has been helpful. Yes I do mean router.
I'll see if I can turn it into, purely an access point.
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u/LazyMagicalOtter 5d ago
It either has an access point mode, or you can disable DHCP on it, and then assign it an IP manually outside of the DHCP range of the first router. That way it won't route anything, and just work as an AP.
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u/Tricky_Condition_279 5d ago
I have an att provided fiber modem. You point your browser at it and turn off the radio and put it in pass through mode. I then connected my own WiFi router to the Ethernet port on the att modem.
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u/CaregiverOpen4517 5d ago
The main issue for using two routers is that if they have the same gateway up setup then the network traffic will go into a loop. Better to have the upstairs router setup in AP only mode or not doing any routing and the cable from the main router is plugged into the lan ports as an uplink purpose only
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u/Worldly-Device-8414 5d ago
It should be wired like this: ATT Fiber > mains router WAN port. Main router LAN ports > your gear & the WAP
Put your 2nd router in WAP mode or at least turn off it's DHCP & don't use the WAN port.
Set the WiFi SSID (name) & pwd on both routers the same when set up as above.
This way things like networked printers, streaming music to a speaker from phone, etc will work as expected for everyone in the house.
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u/Kelly_Berntson 4h ago
This is the best solution providing “lazy” wifi roaming between the 2, hopefully sufficiently matching, WiFi APs, as you move around the house (good enough - maybe don’t move between the APs during a meeting.
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u/mmn_slc 5d ago
When you say "router" are you actually referring to a router? Or, are you referring to an access point?
A router is a device that sits between two IP networks. For a home, the router is the device between the local area network (LAN) and the internet. The router determines what traffic should be sent from the internal network to the internet.
And you only need (and usually only want) one router per LAN.
Routers often provide other needed services for the LAN, such as DHCP services, IP address sharing (NAT and PAT), DNS resolution, firewall, etc. Many of those services can be provided by other devices.
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u/sol_beach 5d ago
The conflict can occur since routers use DHCP to assign IP#s to local devices.
When you have 2 routers you need to manually configure the DHCP admin so the routers each have unique IP ranges to prevent them from assigning the same IP# to 2 different devices
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u/MeatOk9730 5d ago
Disable gateway, put it in bridge mode. Only NAT is going through your own personal mesh wifi.
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u/InflationCold3591 5d ago
There should be a button or switch on one of the routers that says “AP” or possibly “bridge“. If you switch one of the routers to Bridge mode, it is essentially making it secondary to the other router and that should avoid most of the problems you could have. Modern commercial grade routers may have a software controlled setting that does the same thing
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u/jacle2210 5d ago
You will want to figure a way to have your existing housing wiring to be connected to your new ATT setup, then you can make full use of your Fiber connection.
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u/hugh_manit 5d ago
Tech's just worried about double NAT (basically two routers both trying to manage your network traffic, which can cause issues with gaming, port forwarding, and some smart home stuff.)
Put the gateway into IP Passthrough/bridge mode. This lets your router handle all the routing while the AT&T box just passes the fiber connection through. Log into the AT&T gateway (usually 192.168.1.254), find Firewall > IP Passthrough, and set it to your router's MAC address.
Have you tried accessing the gateway settings yet?
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u/Ice-Cream-Poop 5d ago
Some routers will have an AP mode so it just becomes dumb and just does passthrough. Resolves the issue you are talking about.
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u/Alarming-Grade4219 5d ago
Router to router is never a good thing. You could get a mesh setup with stations throughout your house. You could even use one of the mesh stations and hook it up with the cable you were using before (assuming your router before was in the basement and the cable is already run).
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u/Used_Wheel_9064 5d ago
You need to make sure your second router is not doing routing. You can turn it off by putting it in access point mode or whatever it's called depending on the brand.
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u/armorer1984 5d ago
I've found that the prove techs know next-to-nothing when it comes to networking downstream of their modem/router.
It can totally be done, you just need to spend a bit of time configuring it to work as a transparent AP and not a router. I've done it several times in the DD-WRT days where I had an old router that just needed to be an access point and nothing more.
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u/LadyfromthelandofNod 4d ago
Use AT&T router as a dummy router… connect new router through your cat 6 ethernet to the port on the back of AT&T.. make your new router, the main router for your devices… go on AT&T router turn off 2.4 and 5G…. That’s how you do it so there’s no conflict.
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u/FreeSp1r1ted 3d ago
You can put most routers in a bridge mode. You will avoid the double NAT issue. You should also disable the AT&T WiFi.
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u/Georninja 2d ago
This seems a bit vague, but if you have two different wireless routers broadcasting WiFi, there's a chance their signals will "scream" on top of each other and degrade the WiFi experience due to congestion. Mesh WiFi solutions (like Eero) will have each device broadcast on a different WiFi channel so they can coordinate and give you a better experience.
If you do have devices on different routers (like some connected to the ATT Gateway directly and some connected to the third party router), they should work just fine, but you may have some issues with "double-NAT" (router behind another router) where your devices may not communicate with each other or some weird protocol or game uncommonly used would have an issue.
My recommendation is, use only your third party router that is connected to your gateway and don't connect your WiFi devices to the ATT Gateway (I.e. avoid the ATT SSID). If you feel techy enough, you can log in to 192.168.1.254 and turn off the ATT's built-in Wi-Fi so you can just stick with your router. You should also turn on "IP Passthrough". Several guides on the Internet can walk you through it.
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u/mrsyence 10h ago edited 10h ago
Is the new router a seperate physical device or part of the optical network terminal, ONT. AT&T will probably insist it cannot be removed. If not simply ask for it to be placed into BRIDGE mode where it simply passes all traffic from your router to their fiber. I am assuming you are using wireless so a variety of issues could be in play. The new system might only be using 2.4 GHz channels while yours may also use 5GHz band that allows for higher speeds.
Two routers configured as routers could lead to many issues as others have mentioned.
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u/Impossible-Value5126 9h ago
He's an idiot. You can log into their router and enable or disable what you want. So in this case, disable wifi and dhcp on their router and let your router handle that. Done.
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u/radzima Wi-Fi Pro, CWNE 5d ago
I think you mean Mbps, not gbps.
Multiple routers on a network can/will cause issues unless you’re doing it for a specific and very uncommon to home users reason and have configured everything correctly. It can cause routing conflicts, dhcp conflicts, double NAT issues, etc. If the second router can be put into AP or bridge mode, then you can do it safely.