I have a project I want to experiment with
My home WIFI Setup is like this
- I have a main router that's a fiber connection the router is in the second floor.
2 I have a LINKSYS WRT 1900ACS router , that router is in the third floor
So what I did is I installed the ExpressVPN Firmware on the router
(It's based on OpenWRT)
and I set up a wireless bridge between the Linksys and the main router where the Linksys router gets it's internet connection from the main router and spreads the connection to a separate access point
What I want to do now is to have another router that is an LTE router, in case the main router fails to provide internet
the Linksys router should use the LTE router as a backup and get internet access from it instead .
How fast do you need it to fail over? Do you have any hosts with static routes?
With a "simple" dual-router setup, you're at the whim of the clients to change their routing. They typically don't even check to see if the DHCP has changed until the least close to expiring. DHCP changes don't help static-addressed hosts either.
You might want to look at something like CARP for more of a high-availability approach. I believe it may have been ported to Linux.
If you're looking for link redundancy and can accept the "main" router as a single point of failure, then an approach would be to:
- Configure your main router to support the LTE modem as well
- Modify the routing table depending on the link state of the two links
The mwan3 package is one way to manage multiple links https://openwrt.org/docs/guide-user/network/wan/multiwan/mwan3 (I have not used it myself, but there are multiple threads discussing it here.)