The second stage of rebuilding my lab is to have a solid Ethernet and Wi-Fi network.
On this road I bought a few network devices: used HP 2530 series PoE switches.
Built a setup with VLANs separating the home, the planed home automation, guest, etc. networks.
Had some fight with my Mikrotik router to properly support VLANs (still just barely understand its approach of VLAN settings).
I also had Wi-Fi routers, access points (TP-Link and Ubiquiti) laying around. All of them finally converted to OpenWRT.
And the biggest relive that my long hated HP 1920-24G switch also turned to an OpenWRT device (I guess this is a leftover from the 3Com acquisition by HP and the interface is far from the familiar convenient HP UIs):
This correcting my mistake of buying it.
So, most of the logical network setup of my flat and lab is done, just the Multi-SSID Wi-Fi setup and the client device reorganization is left.