(I would suggest redacting your IP… & I’ll go back & obfuscate your ddns address to be on the safe side. Note your ddns address is also in that screenshot.)
To confirm: that nmap scan was executed from the GL device that’s to act as the WG Client, correct? If so the port forward open port certainly looks properly set.
From the Client device, can you post the results of wg show?:
root@GL-AXT1800:~# wg show
interface: wgclient
public key: [redacted]=
private key: (hidden)
listening port: 37692
peer: [redacted]=
endpoint: 37.91.121.99:51820
allowed ips: 0.0.0.0/0
latest handshake: 1 minute, 33 seconds ago
transfer: 5.17 GiB received, 654.82 MiB sent
persistent keepalive: every 25 seconds
I’ll ask the same from the WG Server (Opal). Don’t forget to redact as required.
(If you enclose the output between three ‘backticks’ at the beginning & end (the key by the 1 key), the formatting will be easier to read)