This was for two C20's. I think I found the issue. About 1 out of every 3 reset/power cycles they would work the rest they would not.
Basically, I was using DHCP to assign IP, but manually assigning DNS. You are able to do this on most machines, but the way the Codec handles this is different. It simply appends your manual DNS configuration, including the DNS domain, to the list obtained from DHCP. In a packet capture I was able to see where it would query all 3 DNS servers (1 manual 2 from DHCP) and it would query based on my manual domain and the DHCP domain. It appears to round-robin the response it uses, as all DNS servers responded in one fashion or another, it just picked one to listen to. In this manner, it had about a 33% chance of picking the correct response.
After statically assigning the IP address, the problem went away as the only DNS server was the one manually assigned.
I take this all with a grain of salt though, as our internal team is using the TC7.2.1 code and they get the DNS issue every once in a while regardless of the DHCP/DNS configuration. There may be more to this, but I can say with certainty that using DHCP and manual DNS configuration at the same time is not recommended.
