In my ReadyNAS, the DNS "Domain name" is set to domain.actdsltmp. I don't know how it got that way or what it means, and searching reveals lots of mentions but no explanation I could find.
Does this mean something to someone?
You likely have a cheap modem / router unit that is set to have domain.actdsltmp as the default domain. I wouldn't be surprised if there's some device by Actiontec on the network. Look in the firmware of your modem / router and replace it with a domain.tld that fits your scenario.