After persevering with numerous intermittent hub reboots and calk to help desk, eventually engineer arrived. No issus since 14th May but today 19th May another 2 reboots and when I look at the network log, the same T3 I critical errors logged just prior to the reboot.
VM had previously blamed my 3rd party wifi mesh setup but prior to the engineer visit I disconnected everything from hub and it rebooted that night. After his visit it has been fine until today.
Any ideas?