Unless new location is throttling you after 15 minutes...I'm not at my computer so I can't screenshot it. But, oddly enough seeing as I live in England and London is much closer, it says France is the best server for streaming. But even when using it I still get the FPS drop after roughly 15 minutes. I don't think connection is the issue otherwise I'd have had the same problem with my last processor in my old house.
Whatever the lowest speed you see on the list, take that number and use 80% of it for your buffer and bitrate.
i.e. it says your worse ingest is 2989kbps then set bitrate to 2391.
you can also set your test duration to 5 minutes, Watch your bitrate with Resource Monitor built into windows. right click taskbar and select task manager, to go the performance tab and at the bottom, you'll see "open resource monitor".
This way you can watch it when it drops.
After that all you can really do it call your ISP and tell them the issue.