This strikes me as under-powered from a concurrency perspective.
This plugin uses the Presence system which performs a reasonable amount of client messaging on an ongoing basis to maintain a semi-real-time view of who is online.
With that many clients connecting at once you might consider upping the number of CPUs to at least 3 if not 4 cores. I’m not sure I see the point of 8GB with only 2 cores? I believe one rough rule of thumb is 1 core per 2GB. Even my 4GB machines have 3 cores and I’m not even running this demanding plugin.
Memory and apparently disk space look generous, so no issues there!