How did you install it ? What configuration changes did you make ?
I have your same configuration on LXC in Proxmox but 6GB of RAM without problems with multiple participants.
Might be a network problem. How do you access your VM? Via Internet? Is that VM locally installed at the computer of one of your participants or is it a VM rented from a web-hosting company?
So it’s a VM installed in a Cluster (WorkStation) at a Datacenter. It connected to a 10G switch with 400Mo…
And we access via Internet (i create a DNS for the VM)
So it might be a network problem like it doesn’t has enough bandwitch ?