[bbss]

Agreed, my best guess it's due to a smaller MTU between the CDN and your device. They are probably replying with TLS Server Hello which would typically max a standard 1500 byte packet. It's also likely why HTTP isn't working either since they would ACK the connection, you would probably be able to issue the GET / but you would never get a response back due to the HTTP response payload being larger than a single packet.

A few ideas to test this theory: 1) Find an asset on their server that is smaller than 500-1000 bytes so the entire payload will fit in a packet. Maybe a HEAD would work? 2) Clamp your MSS on this IP to something much smaller like 500 instead of the standard 1460. This should force the server to send smaller packets and will work better in practice than changing your MTU. See: https://tldp.org/HOWTO/Adv-Routing-HOWTO/lartc.cookbook.mtu-...