In the mikrotik, under DNS, I have the Comcast primary and secondary correctly entered.
Package update feature works very unreliably depending which version.
My edge router is currently wide open for testing so I am positive it isn't there. All computers on same network can resolve DNS without issue.
This appears to be a long standing bug which would be great to have resolved and/or some information on which revisions function correctly!

I see this constantly on multiple sites.  It happens a lot more regularly with RouterOS systems behind the primary RouterOS gateway (such as WiFi APs and Dude servers) and it has happened for as long as I can recall - whether manually entered DNS Servers that are pretty much always online (such as 8.8.8.8 (Google)) are used or the RouterOS gateway IP is used, or an internal DNS Server is used.  DNS resolution in the "Check for Updates" is seriously flaky.

And it looks like I found a fix detailed on Reddit - Mikrotik unable to resolve upgrade.mikrotik.com

Basically, it looks like, for some reason, at times the "Query Server Timeout" is changed from the default of 2.000s to 0.000s and the "Query Total Timeout" is changed from 10.000s to 0.000s - resetting these back to defaults has fixed the error whereby I cannot resolve the DNS name, but it obviously is only a temporary fix for the result of the issue and does not at all address the cause of the issue.

So, why do these values occasionally get changed from their defaults back to zero, causing these DNS resolution issues?