Remote play not working for only one user

Server Version#:1.43.0.10231
Player Version#:varies

My girlfriend has had access to my Plex server for a long time and it’s always worked perfectly. A couple days ago though things started acting up. When she’s connected to her home network on any device wired or wireless whatever she watches buffers every few seconds.

Plex doesn’t show relay or indirect play when this happens. Just direct play like always. Nothing has changed on her network, and both of us have fiber internet with plenty of bandwidth. I also have other remote users who are streaming without any issues.

I’ve restarted her router and all of her devices, temporarily disabled firewall to test and changed my server’s public port to a random one (52152). Remote access still shows as fully available outside my network. Same problem.

The weird part is that if she disconnects from her Wi-Fi and uses mobile data on her iPhone, everything streams perfectly with no buffering.

Any idea what could be causing this?

Edit: so using a vpn on her phone did let her stream normally. After changing the plex listening port to 443 her streaming has resumed to normal, I’m not sure if that’s what truly fixed it I’ll update again tomorrow if problem comes back.