Peter Halicky

can you see from the log which one is causing this? I can ping dns.msftncsi.com no problem, also the http request has no issue. I suspect some foul play related to IPv6 (dns.msftncsi.com has A as well AAAA records). However www.msftncsi.com is IPv4 only, which doesn't exactly support that argument.

No, home network. If you tell me what is the DNS query, I can investigate.

yes, 3.2.1.0

Disabling "check internet connection before sync run" actually fixed the problem for me (I do not have any internet connection issues otherwise).

Just for info how this log was created: 1. enable debug logging 2. clear log 3. click "synchronize" and see a ~8-10 seconds freeze of outlook 2016 4. copy&send log (and go back to info logging)

Log attached.

I also have the same problem.