Time to move these hosts up to buster. Test in the vb setup and upgrade the servers when ready.
frmon2001 has been upgraded and looking ok.
Some slowness on auto refresh of grafana panels to start. They would load fresh data or data from a changed window only on page refresh at the start. After about 30 minutes that seemed to clear up. It's possible it was related to caching and coming up from a cold start of prometheus.
There was prometheus data loss for the time period of the reboot as prometheus was not up to collect the data. Aside from that, data was looking ok with both new and old data accessible.
Will let it bake a few more days before doing frmon1001.