It appears that switching to --transport HTTPS from --transport DAV may address the issue. I don't know what we lose by making that switch. We have been using DAV on suggestion from Apple Support for a few years with no issue, given our firewall restrictions we have in place on our network, and I don't know if switching to HTTPS will have any negative effect on our ability to notarize.

This is on a build server that has worked for years - nothing has changed on it or on its network. I sign (as a part of my build) 5 different binaries. A different one fails each time. I was able to take a PCAP from that machine during its build process - and it shows three successful time stamping as and a fourth request (with no corresponding response).

I am seeing this starting this evening - did something happen again?