@Sunshine 

 

Hi Sunshine,

I will try to explain the problem better than last time.

First of all, here is a simplified map of the network:

The main router is managed by my ISP and I cannot alter its configuration myself. The router has a fiber connection and has the DHCP server enabled and is the only DHCP server on the network.

The Archer MR600 v2 is used as a backup router when the main router fails. I can redirect all traffic to the backup router automatically in the event that the main router goes down, but to do this, the backup router must have a fixed, known IP address to which I can redirect all traffic. And this is where the problem arises. I manually assign a fixed IP address to the LAN interface of the Archer MR600 router but the router ignores it and takes a dynamic address from the main router.

I have asked my ISP to set up a fixed lease for the Archer MR600 in the DHCP server settings of the main router, so at least I should know the dynamic IP assigned, but it doesn't work either.

I have also tried setting up a second fixed IP address on the backup router with no success. I have tested with the DCHP server enabled and disabled on the Archer MR600, with no difference (no overlapping address ranges with the main router).

If I disconnect the backup router from my LAN then no problem, the router uses the manually assigned IP address. But in this case, it is useless because I don't use WIFI on my LAN.

This is the ARP table of a computer on my LAN:

As you can see, the MAC address of the backup router appears twice (I have partially hidden it) , once with the fixed IP and once with the dynamic IP. Note: the dynamic IP is different from the one shown in the previous post, now it is 192.168.5.3 and before it was 192.168.5.6.

I have been using the same settings and devices for a while without any problems. Only after updating the router firmware, the problem appears.

I have done a workaround using a shell script that finds the dynamic IP assigned to the backup router and configuring the routes accordingly, but I think the proper solution is to fix the problem at the router.

Thanks in advance.

Regards.

It appears that the upgrade to version 1.7 changed the router's behaviour, causing it to override its manually assigned IP address and take one from a DHCP server on the network. If the router is used in an isolated network, without a DHCP server, the manually assigned address is accepted and everything works as expected. To resolve this issue, you may need to adjust the router's settings or disable the DHCP server on the network. Alternatively, you could downgrade the firmware to a previous version that did not have this issue.

  @marceltrido 

Hello marceltrido,

 

Thank you for your reply. You have explained the problem very well and concisely.

 

I know I can downgrade the firmware version and will do so as a last resort.
I don't know what other settings to change on the router to fix the problem. I am out of ideas right now. I think it is a firmware problem.

 

Regards.
 

  @Binabik 

Hello,

 

I asked my ISP to temporarily disable DHCP on the main router and everything works perfectly as before the firmware update. The Archer MR 600 router took the manually assigned fixed IP address. After turning the DHCP server on the main router back on the problem returned. This is clearly a problem with the firmware update, which is the only item that has changed in my configuration.

 

Regards.