It’s been a difficult spot, and possibly adding concurrent uploads made it worse. Investigation would be wonderful if you’re up to it. You seem very capable. Have you considered a QoS approach to network? Basically have Duplicati upload yield to the latency-sensitive videos. There are forum posts on this e.g.
There also seems to be a OneDrive-specific issue. After I took a guess, its code expert commented in
I’m not the expert of course, but it seemed to me to be similar to the general burstiness problem where Duplicati (not having good control of packet sending, as a router was) throttles by sending timed bursts.
I don’t know if parallel uploads (I’m not expert there either) just lets bursts coincide or added a new bug.
There is no Issue filed for development consideration, but a good-quality issue (steps, data) might help.
I think the throttling algorithm is below. I solved one bug in it, but don’t know the full surrounding context.
https://github.com/duplicati/duplicati/commits/master/Duplicati/Library/Utility/ThrottledStream.cs
From results, this seems to be a workaround, but QoS might be a better one and is more self-adjusting.
That’s good for backups that run at off-hours, but for your working-hour runs, fixed speeds might be fine.
Welcome to the forum, I’m glad your situation is at least a bit better, and I hope you can share your skills.
Duplicati could deeply benefit from skilled contributors in all areas including forum, code, test, and so on.