Router and modem incompability?

[sarnak417]

Hi,

I've had the same modem for some months, which was given by the ISP when I subscribed for a new contract. Since I wanted to extend my wi-fi signal over a 70mt distance I bought an Archer C20i router and a 100mt cat5e cable. I followed the instructions and set up my new router, which seems to work well. At the moment I have 1 PC plus the router plugged into the modem and 2 PCs connected using Wi-fi to the new router.

However when I use 2 computers at the same time, wi-fi crashes on the router and everything connected to its wi-fi gives DNS errors, while modem-plugged pc keeps working. Any idea how to resolve?

 

[Rookie_MIB]

Could be a DHCP issue. Your wired cable modem is most likely a router, likewise so is your new router. Routers use dhcp to assign IP addresses to computers plugged in, and you're only allowed one dhcp server per network otherwise the conflicting dhcp servers get confused.

Try disabling dhcp on the new router...

 

[sarnak417]

Could be a DHCP issue. Your wired cable modem is most likely a router, likewise so is your new router. Routers use dhcp to assign IP addresses to computers plugged in, and you're only allowed one dhcp server per network otherwise the conflicting dhcp servers get confused.

Try disabling dhcp on the new router...

The wired modem is a modem+router, the new one is just a router. Tried to disable DHCP on the new one, same issue. Tried to keep it disable and manually change the new router's IP and well, it got worse.

 

[Rookie_MIB]

Here's the way it needs to work.

1) Plug a computer into the cable/router, let it get it's IP and make sure it's connected to the internet.
2) Find out what the cable/routers IP is. To do this, open up a command prompt (run -> cmd), type in 'ipconfig /all' and hit enter. It'll dump a bunch of stuff, scroll back up until you find the entries for your wired ethernet card. Look for the 'gateway' entry - this will be your cable modems IP address. Write it down. Unplug your computer ethernet cable from the cable/router
3) Find the hardware reset button for your wifi/router. I believe you need it plugged in to power to do that. Reset the router. Plug your computer ethernet into the wifi/router. Get into the management interface like you did. Disable DHCP. Change the wifi/router IP address to whatever the cable/router is +1. So - if the cable/router IP address was 192.168.1.1, change the wifi/router manually 192.168.1.2, and point the entry for the 'gateway' on the wifi/router to the cable/router (in our example, 192.168.1.1).

What this does is create a chain where the wifi/router is on the same network as the cable/router, and traffic is defaulted to the cable router, including DHCP requests. From there the cable/router should properly point outbound traffic out to the internet.

Let me know how it goes.

 

[sarnak417]

Here's the way it needs to work.

1) Plug a computer into the cable/router, let it get it's IP and make sure it's connected to the internet.
2) Find out what the cable/routers IP is. To do this, open up a command prompt (run -> cmd), type in 'ipconfig /all' and hit enter. It'll dump a bunch of stuff, scroll back up until you find the entries for your wired ethernet card. Look for the 'gateway' entry - this will be your cable modems IP address. Write it down. Unplug your computer ethernet cable from the cable/router
3) Find the hardware reset button for your wifi/router. I believe you need it plugged in to power to do that. Reset the router. Plug your computer ethernet into the wifi/router. Get into the management interface like you did. Disable DHCP. Change the wifi/router IP address to whatever the cable/router is +1. So - if the cable/router IP address was 192.168.1.1, change the wifi/router manually 192.168.1.2, and point the entry for the 'gateway' on the wifi/router to the cable/router (in our example, 192.168.1.1).

What this does is create a chain where the wifi/router is on the same network as the cable/router, and traffic is defaulted to the cable router, including DHCP requests. From there the cable/router should properly point outbound traffic out to the internet.

Let me know how it goes.

I'll try tomorrow when I get back to work. However I brought home the router and tried to to this:

Take the ethernet cable from my home modem to a switcher, take another cable from the switcher to ROUTER1 (my home router). Then, take another cable from ROUTER1 to ROUTER2 (the C20i I'm trying to setup at work). Modem and both routers have DHCP activated but on different IP ranges (192.168.1.x modem, 192.168.2.1 and 192.168.3.1 the routers). All my devices and PC at home can interact with these wi-fi signals without problem. So I'm starting to think, could it possible be a broken cable problem at work? Or interference, since it's about 100mt long..

 

[Rookie_MIB]

That could be part of the problem. Max spec length of cat5e cable is 90m, while you could get it to work with longer runs, you can run into issues with longer than spec. If you need to run longer than 90m, they recommend that you split the run and put a repeater (such as a switch or dedicated repeater) in between the two endpoints.

 

[sarnak417]

That could be part of the problem. Max spec length of cat5e cable is 90m, while you could get it to work with longer runs, you can run into issues with longer than spec. If you need to run longer than 90m, they recommend that you split the run and put a repeater (such as a switch or dedicated repeater) in between the two endpoints.

I tried with that you said before, router can't access internet with these settings. So I tried to disable most internet options on my modem, leaving DHCP and NAT enabled and using 192.168.1.X ip ranges, where 192.168.1.1 is reserved for the modem itself, 192.168.1.25 is reserved for the first router (R1) and 192.168.1.50 is for the second one (R2). Then I took a single cable from the modem to a switcher, and from this one single cable for each router.

Then I set R1 with DHCP for ranges 192.168.2.X and R2 the same with 192.168.3.X range. I connected all devices to R1 using wi-fi only, and they all work flawlessy. However, when conneting the other devices to R2 wi-fi, internet is INCREDIBLE SLOW and the loss of packets it's really high.

From the modem I also noticed that R1's hostname is visible (Archer_C20i), while R2's hostname is not calculated (shows ---). I think my only chances are either the long cable that powers R2 being damaged or R2 itself partially broken?

 

[sarnak417]

Seems like I fixed it in the end..

Deactivated all internet functions except DHCP/NAT on modem + forwarding every single port on it for a specific IP. Then I plugged a single ethernet cable from it to the first router and assigned it the IP chosen from before, leaving DHCP active for a different "class" of IPs. With another cable I plugged the second router to the first one, still leaving DHCP enabled on another class. Now I can connect to these 2 separated-but-interconnected wi-fi without causing any incompability.

 

[Tinamaxico]

Please change the ip address of your router. then it will start working fine.

 

[livejog]

Please make the ip address in different class. if your Modem has c class Ip address then change the router's ip address into A Class or B class.