Routing problems with LTE modem in L3 bridge mode and ASUSWRT Merlin (AC68U)

[Lord Lovaduck]

My ISP uses a Telrad 8101 LTE modem (I wonder if that's the correct term, modem?) which can operate as NAT/Router, L2 (GRE) bridge and L3 bridge. Yesterday I tried to set it up as L3 bridge to avoid double NAT with my router running AsusWRT Merlin 384.5 level. This option "almost" worked... I had some weird problems. It is possible to reach many web sites, some like Facebook or Amazon come up without a problem. Others, I can ping and find out their addresses (ping -a www.google.com for example). When I use a Chrome or Edge to check the site, the name is not accepted but the IP address obtained from Ping does work. I am not an expert in IP so I guess some configuration is required and probably my router is partially recognized but not fully. I tried specifying 8.8.8.8 as DNS server instead of the ISP provided one (through DHCP) but makes no difference.
My next experiment would be to clone the original LTE modem Mac Address to the router WAN interface to see if that works, but not sure, I don't know if it is still used in the background and then I'd have a duplicate.

I tried L3 as it was described in one of the Telrad's manuals. I have not tried l2 (GRE) bridge mode yet.
Any ideas? Are there any relevant parms on the AsusWRT I need to set up?

BTW I called the ISP and they refused to set it up in bridge mode themselves so I am on my own on this....

 

[noyp]

My ISP uses a Telrad 8101 LTE modem (I wonder if that's the correct term, modem?) which can operate as NAT/Router, L2 (GRE) bridge and L3 bridge. Yesterday I tried to set it up as L3 bridge to avoid double NAT with my router running AsusWRT Merlin 384.5 level. This option "almost" worked... I had some weird problems. It is possible to reach many web sites, some like Facebook or Amazon come up without a problem. Others, I can ping and find out their addresses (ping -a www.google.com for example). When I use a Chrome or Edge to check the site, the name is not accepted but the IP address obtained from Ping does work. I am not an expert in IP so I guess some configuration is required and probably my router is partially recognized but not fully. I tried specifying 8.8.8.8 as DNS server instead of the ISP provided one (through DHCP) but makes no difference.
My next experiment would be to clone the original LTE modem Mac Address to the router WAN interface to see if that works, but not sure, I don't know if it is still used in the background and then I'd have a duplicate.

I tried L3 as it was described in one of the Telrad's manuals. I have not tried l2 (GRE) bridge mode yet.
Any ideas? Are there any relevant parms on the AsusWRT I need to set up?

BTW I called the ISP and they refused to set it up in bridge mode themselves so I am on my own on this....

View attachment 14233

Hello, were you able to figure out how bridging works in telrad, looks like i have the same interface with your lte router and planning to bridge it

 

[Lord Lovaduck]

Hello, were you able to figure out how bridging works in telrad, looks like i have the same interface with your lte router and planning to bridge it

No, thankfully I got a new fiber connection shortly after my post, with a GPON bridge... Unfortunately, I can't give you any insights on this!