Hello
We have the same issue in Excel with "Save As" using a DFS virtual path.
While the message is displayed, we can observe the computer trying to connect to each Domain Controller of our domain oh HTTP port 80 !!!!
Fortunately it fails with SYN_SENT TCP messages.
C:\Users\PBALVERDE>netstat -an 1 | findstr SYN
TCP xxxx:57610 yyyyy:80 SYN_SENT
TCP xxxx:57610 yyyyy:80 SYN_SENT
TCP xxxx:57610 yyyyy:80 SYN_SENT
.....
TCP xxxx:57610 zzzz:80 SYN_SENT
TCP xxxx:57610 zzzz:80 SYN_SENT
TCP xxxx:57610 zzzz:80 SYN_SENT
....
(whe yyyyy and zzzz are two DCs)
If this info could help the community to resolve the issue...
Best regards.
WM.