I tried everything, and I think I finally found the culprit. In Windows Defender Firewall with Advanced Security, 24H2 does two things: (A) disables all File and Printer Sharing rules, and (B) adds a bunch of rules called File and Printer Sharing (Restrictive) [blah blah blah].
In some cases, even if (A) is not done, (B) is done and something else is disabled that breaks file sharing.
The solution is:
- Go to Windows Defender Firewall with Advanced Security => Inbound Rules
- Scroll down to File and Printer Sharing. Look at column "Profile" and make sure all rules with your correct Profile are enabled (right click - enable)
- Enable all items at the bottom which have the word (Restrictive) in the name. The most important one is called File and Printer Sharing (Restrictive) (SMB-In).
To be clear, just enabling File and Printer Sharing (Restrictive) (SMB-In) should do it, but I went overboard to make sure the computer responds to pings, etc.
Thanks for this Andrew - but afraid it didn't work for me and my 24H2 PC. I have tried all the suggestions I can find, including yours, but nothing seems to work. My Netgear router USB attachment (Readyshare) doesn't show under Networks, nor do any computers on the home network. Interestingly, the only thing that does show up is a Synology NAS. However, the problem 24H2 computer shows up fine on my other 23H2 computers on the network. Please post if you come up with any other suggestions!