Hi,
Yesterday, we noticed that two (out of three) RDS servers that are running on Windows Server 2019 started having some issues.
When our users try starting Outlook, a window pops up and says (translated from Swedish) that "It's not possible to connect right now. Check the network and try again in a while". Internet access and browsing does however work without any issues.
I signed in with an administrative account and I can see that the network symbol has a yellow warning sign. If I click on it, it will say that it's connected to the domain but that there is no Internet access.
We did some troubleshooting and eventually ended up restoring the VMs to a point before the February patches had been installed, thinking it was related to those. However, there was no difference. The issue is still there.
Now, I've been trying to troubleshoot this in every way I could think of. I've have
- Checked the logs, cannot find anything that seems to be related to this
- Reset TCP/IP
- sfc /scannow
- dism
- Switched from static to dynamic IP
- Tried a different gateway and DNS servers
- Removed virtual NIC and created a new one, even with different drivers
- A bunch more things that I can't think of now.
When I eventually figured I'd install Wireshark (with npcap) to sniff some traffic, it miraculously started working. I reset to snapshot and tried again with the same result - working. I tried it on the second RDS with the same issue - it works. I even tried
applying the patches and removed Wireshark and it still works. However, to get it working it actually requires that you start a logging session.
No, I can't seem to get my mind around this but it feels as if something is wrong with the Windows network stack but I don't really know what else to do about it. I'm not really happy about seeing this as good enough, I would rather understand the issue
and try to apply a "real fix" as I'm not sure if this is going to be a permanent solution.
I would appreciate any help with this.
Cheers.