My main router and one set up as a client bridge will talk to each other with better speed and robustness using AC (VHT80) modes than AX (HE80). I can't figure out a way to leave the main router in AX mode and tell the client to use AC modes to connect. No mode that I specify in OpwnWrt is honored in the client. So I can only get the client to connect in an AC mode if I downgrade the entire net to AC at the router.
Is there a way to have OpenWrt honor the modes set on the client?
Did you try rebooting the client bridge after changing to AC mode? I don't know if that will work, but sometimes it is necessary to reboot to get certain hardware settings to take effect even if luci doesn't prompt you to reboot.
according to my understanding the WiFi config in the „Edit“ section affects Wifi Access Points only, not the client mode that gets triggered via Scan->Connect.
Fair enough. The settings perhaps need to be greyed out in other modes.
Question is, is there a solution? Is there any way to impose a modulation restriction on a client connection? I see openwrt's iwconfig/iwlist doesn't support the "modu" command.
Correct.
Such settings are made on an AP. You seemed to have identified that already, though.