Has anybody had trouble with wifi calling on T-Mobile?
I have frequent call dropps with heavy torrent downloads.

Any thoughts on a remedy (besides "stop downloading" and "don't use wifi calling")?

try backing off your download and/or upload speeds a bit. or try running with the bandwidth auto-limiter on.

If you use your Internet pipe to the Max of course you are going to have issues, dost matter if its Torrents, HTTP or FTP.

Set your Torrent Cleint to maybe 10-15% of your Max Download/Upload of your connection.

Or better yet setup QOS on your router, or get a router that allows you to.