Might be worth adding, I’m a network and system admin, so not a complete novice.
I might be overlooking something but I can’t figure out what…
I’ve even tried tweaking the server.ovpn file on the GL.iNet after connection over SSH, and editing the config file using vim with various settings (ciphers, etc…)… No success.
$ vim /etc/openvpn/ovpn/server.ovpn
$ /etc/usr/sbin/openvpn --config /etc/openvpn/ovpn/server.ovpn --daemon --writepid /var/run/ovpn_server.pid

Something is wrong with the implementation I believe…
My GL.iNet firmware is 3.216, and the Network Mode is Router.
WiFi is enabled and waiting for connection from clients
Internet is provided from a Modem Router (LAN) cabled to the GL.iNet WAN port (RJ45 / Cat 5E)