I've recently deploy pi hole, and everything seemed fine for about a week. Then I restarted my steam link (steam streaming device). It could not find my home pc on the same subnet that it has been able to find fine for the past 6 months. Disabled windows firewall thinking it was a pc issue, same thing. even moved the steam link right now to my pc and plugged into the same switch. Same isssue.
I only discovered that it could be a pi hole issue after I set a static IP AND DNS for the steam link. Once I did that, everything seemed to work. So I decided to back off the static and rock with DHCP (which of course the pi hole dns entry is distributed), rebooted the steam link and the link could not find the pc again. Changed dns entry in the DHCP server and tried again. Eureka! Steam link would work once again. I of course rolled the changes to my dhcp server back and just statically assigned the steam link, but something Pi hole is blocking that the steam link doesn't like.