Slow internet in GL-MV100 (Brume)

I am trying to do a site to site VPN, using my home internet as a server.
I have 2 GL-MV100 (Brume) routers. One of them as a server connected to my home modem and the other one as the client connected to a different network/modem. I wanted to connect one to each other. I tried the OpenVpn and also the Wireguard, however none of these type of configuration give more than 20mbps on the client router and I was told with the GL-MV100 (Brume) router I would get a higher internet speed with the Wireguard configuration.

Both modems providing internet to these router (the server and the client) have good internet speed of 900bmps.

What can I do to get a higher internet speed in the client router?

Can you confirm what is your ISP upload speed? The upload speed will be cap for the vpn speed.