HA stopped responding on local network via external URL - No changes made

Hey folks, kindly ask you help here as I’m running out of ideas. Suddenly lost my external access to my HA when accessing to https://xxxx.yyy:51020/


Please no changes have been made that might led to this disruption.
My setup:
RPi 4 8gb
Home Assistant 2023.5.3
Supervisor 2023.04.1
Frontend 20230503.3 - latest
Network config @ HA
→ External URL -->> https://xxxx.yyy:51020/
→ Internal URL: -->> http://111.222.333.444:8123
Nginx configured for port 8126
Port fwd on my router from 51020 to 8126 over private HA IP. (validated port is open externally)

What kind of logs can help me on troubleshooting?

Thanks in advance.

I assume nginx is doing the ssl termination and reverse proxying https/8126 → http/8123 ?
What happens if you try to access https://111.222.333.444:8126

It’s now sorted.
Reconfigured NGINX port to 51020 and external url to 51020 as well.