Thanks to the good tips here with the change to the cloudflare DNS servers and the DNS flush, the uploads here are running again.
Servers are in Falkenstein, Germany, running Ubuntu Server 22.04. We haven't changed anything in our rclone commands.
Our DNS change commands:
sudo nano /etc/netplan/01-netcfg.yaml
Change the nameservers in this file:
name servers:
addresses:
- 1.1.1.1
First try whether the network is still reachable after the changes:
sudo netplan try
If everything works:
sudo netplan apply
Clear DNS cache:
sudo systemd-resolve --flush-caches
Check if the cache has been cleared:
resolvectl statistics
If the answer there is 0 under size:
cache
Current cache size: 0
the DNS cache was emptied.
Even without a reboot it has been working for us ever since:
Transferred: 38,780 GiB / 38,780 GiB, 100%, 62,606 MiB/s, ETA 0s
Checks: 8 / 8, 100%
Transferred: 8 / 8, 100%
Elapsed time: 8m15.6s
I.e. the uploads run more or less normally again with approx. 600-700 MBit (although they almost always ran with 1 GBit before the upload lock, but it doesn't matter).