Trying to connect message when Saving in Excel 365

I suspect early October for the Current Channel and November 9th for the Enterprise Monthly Channel, but it is possible it may be earlier.

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.

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.

Are your DCs also hosts of DFS then? That would explain this behavior.

From what I have discovered the problem is that instead of using the provided path as a UNC path (over SMB), it is first contacted using webdav (which is the port 80 request). When the server doesn't respond to port 80, it will eventually time out which is why the message box is displayed on screen that it is trying to connect. As soon as Outlook/Excel stops the connection attempts over webdav, it tries to connect using port 445 and as DFS/File servers accept these connections, you will be prompted with the window asking you where to save.
I already posted my findings on a different forum so I won't repeat them here.
The TL;DR version is that if you want another workaround for this (at least one that worked for me) is that you can set an outbound block rule for port 80 on the client to the server(s) hosting the fileshare. Only an outbound block worked for me, creating an inbound block on the server-side did not work.

Hope that helps anyone

For us the Windows Firewall solution mentioned by Rockspice on Aug 24th, 2022 at 8:27 PM worked:

https://community.spiceworks.com/topic/2458452-saving-files-to-unc-path-in-ms-office-365-is-really-slow

"[...] I made a custom outbound rule on the Windows firewall blocking port 80 traffic to the target server. [...]"