[ovirt-users] Host non-responsive after yum update CentOS7/Ovirt3.6

Hi, I working on a CentOS7 based Ovirt 3.6 system (ovirt-engine/db on one machine, two separate ovirt vm hosts) which has been running fine but mostly ignored for 2-3 of years. Recently it was decided to update the OS as it was far behind on security updates, so one host was put into maintenance mode, yum update'd, rebooted, and then it was attempted to take out of maintenance mode but it's "non-responsive" now. If I look in /var/log/ovirt-engine/engine.log on the engine machine I see for this host (vmserver2): "ERROR [org.ovirt.engine.core.vdsbroker.vdsbroker.GetCapabilitiesVDSCommand] (DefaultQuartzScheduler_Worker-36) [2bc0978d] Command 'GetCapabilitiesVDSCommand(HostName = vmserver2, VdsIdAndVdsVDSCommandParametersBase:{runAsync='true', hostId='6725086f-42c0-40eb-91f1-0f2411ea9432', vds='Host[vmserver2,6725086f-42c0-40eb-91f1-0f2411ea9432]'})' execution failed: org.ovirt.vdsm.jsonrpc.client.ClientConnectionException: Connection failed" and thereafter more errors. This keep repeating in the log. In the Ovirt GUI I see multiple occurrences of log entries for the problem host: "vmserver2...command failed: Vds timeout occurred" "vmserver2...command failed: Heartbeat exceeded" "vmserver2...command failed: internal error: Unknown CPU model Broadwell-noTSX-IBRS" Firewall rules look identical to the host which is working normally but has not been updated. Any thoughts about how to fix or further troubleshoot this?