ESXi 6.0 hosts intermittently disconnecting and reconnecting to VCSA 6.7

[vmJustinS]

Recently upgraded our VCSA from 6.5 to 6.7. Once on 6.7, we noticed our 6.0 hosts randomly disconnect and then reconnect approximately 19 minutes later. The frequency of this occurring is maybe 4 times per day and seems to be randomly distributed amongst the hosts. Most times only one is down and the others are up. During this time they are actually inaccessible on their management interface, not even responding to ping.

I have rebooted hosts, I have also tried removing and re-adding hosts.

Thanks in advance for your help.

[MaxB]

I poorly remember an issue in Version 6 that the vpxa ran out of memory. But this should have been fixed, as long as you updated. Which Update/Patch are you running? 

(is there anything that blocks an Upgrade to a newer version? 6.7/7.0? )

[vmJustinS]

The hosts are on build 15517548 and compliant with all critical and non-critical patches.

Unfortunately 6.0 is the latest release compatible with the server hardware. We have the VCSA on 6.7 in preparation to migrate to a new datacenter but that hasn't happened as quickly as we would've liked.