Very slow Internet after installing BWM on KVM virtual machine with VPN

Hi. I installed Bandwidth Manager on my KVM virtual machine after finding that the previous software I was testing, Netlimiter, crashed the virtual machine upon install.

I'm using Zerotier one as a VPN to access the virtual machine through the router firewall, and I suspect something about the KVM virtual NIC, or Zertotier, or the combination of the two, might be what's causing the Internet traffic to slow to a crawl.

I'm not sure what the cause is, but some traffic is fine, such as my cloud sync app, and speedtest.net, while other traffic is dead slow. Web browsing seems ok, but as soon as I download a file off the web, suddenly there seems to be some problem, and the files download at about 0-80KB/s.

I tested uninstalling Bandwidth Manger on one of my two identical KVM virtual machines, and the download speed seemed to have returned to normal.

Yes, it's likely to be a conflict between the apps, or more specifically, between their drivers.

Was that with any rules defined in the Bandwidth Manager? Is there anything in the Event Log?

I'm getting dcom errors in all my virtual machines. Regardless of having any software installed.

Errors like this are coming up in the event log. I'm not sure if this could be related to what's causing the problem with bandwidth manager.
Maybe it's some issue with the drivers for the KVM virtual machine.
I was having a memory leak problem caused by the KVM balloon driver, which was supposed to allow for memory management inter-operating with the KVM. I disabled the balloon driver which fixed the memory issue. But perhaps there's other KVM drivers that aren't working well.