ethernet router + lte router - please advise configuration

Hello,
I have main router CRS112-8P-4S and router on attic RBM33G POE powered with 1 LAN cable (both running stable ROS 6.47.7) with LTE modem. I would like to pass LTE connection directly to CRS112 and do it safe way.
What should I do?
Should I connect second LAN between CRS112 and RBM33? (to maintain software updates and maintenance)
And how to bridge or exclude from bridge ports?
for all suggestions many thanks
Maciek

Configure the rbm33g as router and do all fireballing on it.

Configure crs112 as a switch device, i.e. Bridge all ports and no firewall etc

sorry, I forgot to mention that my CSR112 is acting as CAP manager for 2 x CAP AC access points

I’ve set mine up using a separate subnet between the main router and the LTE router. The interface that connects the main router to the LTE router is added to “LAN” rather than “WAN” interface list, so the main router does not do NAT. Added a default route on the main router pointing the LTE router. And a route added to the LTE router for my home subnets via the main router.

With this configuration I can still manage the LTE router from the main network.

CAPSMAN will not change the picture, but I really do not see the purpose of CAPSMAN with only 2 APs, adds unnecessary complication, if you had 10 x APs then maybe a different situation

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