Issues with DNS and 5GHz wireless

I am currently running the 378.55 build on a RC-AC87U and a RC-AC68U and I have noticed a problem with DNS resolution under both builds - in particular on the wireless side. I am doing nothing spectacular with either - both have had factory resets performed on them, both were running in Routing mode (though I have also noticed the same thing happen in Access Point mode).

Essentially what is happening is this;
- After ~2 days of operation under normal traffic conditions (say 2 people using...

Issues with DNS and 5GHz wireless