Recently had a weird one – Veeam kept reporting that it could not download the .vmx files for particular virtual machines. These VMs all had one thing in common – they had ran (or were running on) a particular host. But that host looked fine to me – like any other hosts in the cluster.
Turns out, that host was missing a domain in the list of search domains for the TCP/IP stack. I had a.example.com, but I also needed other.a.example.com!
Added that in, and things started working just fine.