Homelab

I want to link my brother's network to my own in the lowest maintenance and power consumption way possible. I want to be able to remote admin the computer and for his devices to access my network storage and potentially other stuff eventually.

My home network: Cable modem from ISP in bridge mode AliExpress Intel n100, 4x i226v, running opnsense bare metal Generic switch Wifi AP Multiple old computers and sbc's for self host stuff and 3d printers. Tons of wifi devices due to 10 person household.

Brother's network: ISP modem with built in wifi in default mode. Everything is wifi except tv and the previously mentioned computer. 2 person household.

I had previously tried using wireguard on an openwrt router on both ends, one a nanopi r5s and the other an orangepi r1 plus lts. I think I ran into issues with being unable to install packages due to being out of date or something. I tried compiling openwrt myself but it would fail and diagnosing that was beyond me. At the time the r5s was my home router.

I'm looking for recommendations for how I could connect at least his wired devices as if they were part of my network. Unfortunately it seems I'm still at the point where I don't even know what I don't know when it comes to networking.