If it's timeout error and you increased the "Timeout" option -> report to them, it's their server issue.

Right after last update I started getting upload speed limit via api. It randomly just starts uploading no faster than 300-400k and it's 1g server.
When I stop the upload via api and retry it goes full speed. I see no pattern, it just happens whenever.
I tried rebooting server but it kept happening.
I'm using web upload at the moment and I didn't face any problems so far.
Update:
This random thing is also happening with fikper api upload.

There were no changes at all for these hosts for at least a year in my side.

It's something at their side.