On 26/11/2020 06:40, Richard Kimberly Heck wrote:

This problem seems to have been solved. I believe that the issue was a misconfiguration of the NFS server. I had:

/home/rikiheck/files           192.168.1.0/24(rw,sync,no_subtree_check,fsid=0)
/home/nancy/files              192.168.1.0/24(rw,sync,no_subtree_check)
/home/photos                   192.168.1.0/24(rw,sync,no_subtree_check)
/multi                         192.168.1.0/24(rw,sync,no_subtree_check)
/git                           192.168.1.0/24(rw,sync,no_subtree_check)

But /home/rikiheck/files was an ordinary directory that I want to export, not the root for NFSv4. It was being mounted as NFSv3 (trying to mount with nfs4 would fail). But I'm guessing that it was being treated inconsistently between the client and the server. Removing the 'fsid=0' tag solved the problem. It's still a bit of a mystery what exactly the firewall was blocking, but it wasn't a firewall problem, in the end.

Thanks to everyone who offered suggestions and advice, especially Ed Greshko.

Probably I will take the opportunity to move anyway to NFSv4, now that I've done all this reading about how to do that!


Happy to hear it is all working.

Be careful that you don't read articles that are outdated on NFSv4.  Things have changed and there is no need
to do bind mount or something like that. 
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The key to getting good answers is to ask good questions.