My question is this... does relayd/luci-proto-relay package have to be installed on the main router, or just the client router? I ask because I want to use the ISPs router as the main router, and set up the relay configuration as described in the article using the OpenWrt router I'm setting up that has the relayd/luci-proto-relay package installed as the client.
The instructions don't mention setting up the main router with the packages. Just wondering if this is going to be possible or if I need to set up two OpenWrt routers one as the main router and one as the client/repeater.
I don't know if the ISP router supports WDS mode, but I'll experiment and find out. Also going to look at kmod-trelay package to see if that improves on the relayd packages. Three packages and three different approaches to solve the same issue. I know my ISP sells mesh extenders themselves - but at a super-premium so I'd rather get the reclaimed OpenWrt router doing the job. A mesh setup is a fourth solution, but I know that requires two OpenWrt routers.
relayd is for when the main router does not support WDS. It does not require anything from the main router other than an ordinary AP-client connection. So it can be any type or router even one that you don't own but have permission to connect to.
If you don't need to access the main router's lan, as would usually be the case with "router you don't own", use a regular Routed Client instead of relayd.
If the main router does support WDS, is that the optimal way to do this? I'm going to try all the suggestions and see what works. Marc_r 's solution had not occurred to me before. I've been able to get the client router to connect to the main router fine, but it's a double NAT and different SSID on the client router.