FWIW, my symptoms were very similar, but different. I have 3 PVE hosts which each have an iSCSI connection to a virtualized instance of TrueNAS. I'd keep seeing the following messages:
Nov 11 09:12:28 truenas 1 2020-12-09T22:12:28.797576+01:00 MYDOMAIN.tld ctld 63152 - - 86.75.30.9: read...