So I have a Offsite server on a master router, (to maintain name server compatibility) and I have a glinet router on lan too. on Different subnet (LAN) but the same subnet for internet.
And I vpn into the offsite location to have a permanent location for offsite backups for work.
So I must have the Wireguard VPN on my router as a Client as on the other side The target NAS is not on the VPN router its on the main router.
so for this reason I cannot have a open VPN connection
This isn’t your server address. Pretty sure. It might be a mixture of user, password and server - but it’s not the server address, whether for OpenVPN nor Wireguard.
They might use some special protocol which is not supported by an GL iNET router.
And if your provider is “DuckVPN.com” - I would highly recommend changing it. The whole website looks terrifying.