Ubuntu 22.04 unable to use JetBlue inflight wifi

I have Ubuntu 22.04.3 running on an Asus Zenbook, exact model UX390UAK. My wifi at home and in coffee shops works fine but on every JetBlue flight I take I'm unable to use their inflight wifi (called FlyFi).

The network connects but the login page (flyfi.com) is unable to load, it appears to fail at TLS negotiation.

Here are things I've tried:

• Change DNS to Google - without this the login portal (FlyFi.com) doesn't resolve at all
• disable IPv6
• disable ufw
• disabled MAC randomization
• update openssl config to allow UnsafeLegacyRenegotiation, allow TLS v1.2, and set Sec level to 1
• various MTU from 500 to 1500
• restarted NetworkManager between all of these steps

Some other details:

• I keep my laptop updated regularly, I was last on a flight in Jan and the same problem occured (also JetBlue)
• Chipset is Intel 8260
• wifi works on phone running Android (same scenario in January)
• testing with openssl -connect gives errorno=104 - it seems the server just isn't sending any data (it also shows messages like no peer certificate available and No client certificate CA names sent
• running curl -k https://www.flyfi.com or when loading in a browser (tested both Firefox and Chrome) it ends up with Connection reset by peer while negotiating TLS
• no obviously relevant error/warn messages in journactl nor dmesg

I'm at a loss for what else to try/look into. Any ideas on what could be the root cause or other debugging steps to take?