This is an example URL that times out for me:
curl -i https://archive.ubuntu.com/ubuntu/dists/focal/InRelease
Checking with netcat:
$ nc -vv archive.ubuntu.com 443 nc: connect to archive.ubuntu.com (2620:2d:4000:1::16) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (2620:2d:4000:1::19) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (2001:67c:1562::18) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (2001:67c:1562::15) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (185.125.190.36) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (91.189.91.39) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (91.189.91.38) port 443 (tcp) failed: Connection refused nc: connect to archive.ubuntu.com (185.125.190.39) port 443 (tcp) failed: Connection refused