Asus ROG Rapture GT-BE19000: Most stable firmware and features to disable?

[caisersouze]

In the left screenshot, towards the right side there should be a -> More Config

Use same subnet as main network should be toggled off, creating a VLAN. If this doesn't help or it is already toggled off someone more knowledgeable is going to need to chime in...

Thanks a lot for your suggestion! I recreated the MartinRouterKingVPN as custom network not vpn network and left “Use same subnet as main network” disabled, and now everything works perfectly: any client that connects to that Wi-Fi is correctly routed through NordVPN.
Really appreciate your help!