Reappearing "You need permission to perform this action" error in W11 when accessing TrueNAS password protected SMB share

Core 13.3, W11 updated daily:

When trying to copy a file from W11 Downloads to a TrueNAS SMB share I get “You need permission to perform this action”.

The Share and File system ACLs are both set to FULL control for everyone, group and owner.
The share access is controlled by user name and password.

When originally, about a month ago, I had a similar problem when SMB signing made its way into W11 in the 24H updates, I changed this share from guest access to password protected access and, in the Group Policy Editor, explicitly disabled all the SMB signing requirements and changed a few things in the Lanman workstation part, everything worked well.

However, after a while the “You need permission…” message started to reappear. Then I went into the group policy editor, and discovered a few completely new items that were Not Defined.
I defined those as well as I could, and then things worked again for a week or so and then, yesterday, the error message reappeared.

I found a few more Not Defined items in the policy editor and tried to do away with those, but this time nothing seems to help.

I have worked around the immediate problem thru booting Linux Mint (and Ubuntu) from other partitions on the main disk and then moving files from the Windows C: partition to the TrueNAS SMB share in Linux. That works perfectly.

Can someone come up with some idea how to solve this, or suggest some good and to-the-point documentation on How To Mount SMB Shares While Avoiding The Evil Signing Monster, or suggest how to do this W11 operation in a way that tells me more about the details of the problem?

I assume things can be done in some logging/debugging/stepwise manner that might show the real reason behind this problem.

It turns out that what had changed this last time was that numerical IP addresses no longer necessarily work.

When I changed around a few things I could use a symbolic server name and mount the share thru that and, knock on wood, it has worked for a few hours now…

My issue with Micro$oft error reporting remains valid. It should be possible to give precise reasons for such failures.

…and I was wrong again…

It stopped working again.

WHAT the hell???

I did get a complaint that there is no domain controller to service my request??
Why did that happen now???