immich runs via docker-compose behind nginx-proxy with acme-companion with wildcard cert.
I verified immich works both internal (same fqdn resolves to internal ip) and public (router is setup correctly). In both situations I get a valid lets encrypt wildcard cert.
The above is tested from Windows 11 and Linux (Ubuntu with Firefox) internally, and from remote locations over the internet.
My Macbook pro M1 with latest macOS accesses the site via web browser. It works fine too.
My iPhone however refuses the load the site via wifi. When I disable wifi, the site loads fine.
The app shows the same behavior. Via wifi it refuses to connect but via mobile data it works fine.
After switching off wifi, the logs show the error in the screenshot.