I'll have to "upgrade" my Mac to Tahoe 26.4 first to do some testing.
Will reply later this afternoon 😊 

Note: I thought Windows doesn't like it that one mounts without login credentials? Since you mentioned that all worked will with Tahoe 26.3, I'll assume I'm recalling that wrong.

Just upgraded to 25.4 and ... ConnectMeNow mounts shares to my NAS just fine.

One thing though, a notification appeared asking me if ConnectMeNow is allowed to find devices in the local network.
Did you get this message, and if so: did you click allow?

If you missed it, you can find it under:

System Settings -> Privacy & Security -> Local Network -> ConnectMeNow4.app should be enabled.

Please let me know if this fixed the issue. 😊 

The System Settings -> Privacy & Security -> Local Network -> ConnectMeNow4.app setting is enabled. I've tried disabling and re-enabling it, and it doesn't seem to make a difference; I still see the same behaviour.

Thanks for the question about the login credentials. I'd temporarily disabled the login option for my share while testing, but I see the same "NetFSMountURL: Error - Mount failed (Error code: 1)" error message when it's enabled. (My share definitions all include login credentials for the remote shares on the Windows PC.)

10:44:27 │ Mount requested for: "SMB RPGs"
10:44:27 │ - Max Attempts = 1
│ Attempts Left = -1
│ Last Attempt = n/a
10:44:27 │ - Doing default short mount delay (1 second)
10:44:28 │ - Starting mount background task
10:44:28 │ - RETRY MOUNT TIMER: Started 1 minute timer for remount attempts
10:44:28 │ - Enabled timer for potential extra mount attempts
10:44:28 │ - Thread started

10:44:28 │ Mount status update:
│ Mount/Open Networkshare feedback (SystemDefault):
│ Mount attempt with Calling Apple NetFS API:
│
│ - LOGIN: Username and Password known - User login with hidden window
│ URL: smb://myPC/D/Users/myUserName/Documents/Gaming/RPGs
│ Mount directory: macOS will mount against a mount directory in "/Users/first.last/myPC"
│ - NetFSMountURL: Error - Mount failed (Error code: 1)

10:44:28 │ Thread - Calling for forced status update (only shows results if something changed)

10:44:28 │ -- STATUS UPDATE - THREAD CALLBACK ------------------------------------------------
│
10:44:28 │ Update type
│ - Initial read : -
│ - Timed Interval : -
│ - Get Network info : -
│ - Forced Update : YES
│
│ Status Interval : 10000 milliseconds
│ Interval Interrupts : 500 milliseconds
│ Failed mount after : 30000 milliseconds
│
│ Default gateway : 192.168.1.1 (MAC: 24:41:FE:60:15:BB)

The smb://myPC/D/Users/myUserName/Documents/Gaming/RPGs share URL works in Finder.

If I mount the shares using mount commands in Terminal, ConnectMeNow me mount notifications for them and displays them with the green "mounted" icon, so it can tell when they're mounted. And I can unmount the shares using ConnectMeNow; I just can't mount them using it.

Is there any way I can capture more details in the debug logging? The NetFSMountURL error message is pretty generic and I can't tell why the mount operation is failing.

For the record, if I disable the System Settings -> Privacy & Security -> Local Network -> ConnectMeNow4.app setting, the failure mode changes: my mount attempts all produce nice clear "Mount attempt aborted - Server ping failed" notifications. So ConnectMeNow definitely has local network access, and my issue appears to be unrelated to that setting.

More findings:

I can successfully connect an SSH shell share on the same remote Windows 10 PC, so the issue appears to be limited to SMB.

There are two SMB fixes listed in the macOS Tahoe 26.4 security release notes: https://support.apple.com/en-us/126794 Since my issue only affects SMB (as far as I can tell at present), and only started after I "upgraded" to Tahoe 26.4, I'm wondering whether Apple's SMB fixes changed some SMB behavior that ConnectMeNow relies upon.

So I managed to access a share on a Windows machine.

Option 1 - Do not use a custom path

Took me some effort, under "Advanced Options" I had to check "Default (in /Volumes)" to make it work.
As I never really use this, I had to set permissions (under Windows) for myself to get access (regular username that I use for login, and the password of Microsoft account).

Option 2 - Use the Commandline Mount Style

What also works, if you need a custom path: Set the "Mount Style" to "Commandline":

Seems Apple introduced a new "feature"  ... AKA broke using the NetFSMountURLSync for custom paths.

p.s. bug reported at Apple - will see how this develops.

Thank you for the update and the workaround suggestions! Switching to Commandline worked for me. And thank you also for reporting the bug to Apple!

I very much regret trying this ... this wasn't the only thing that this update broke 😞 

But I'm glad I could help 😊 

Posted by: @hans

↑

I very much regret trying this ... this wasn't the only thing that this update broke 😞

Yes, I wouldn't have moved to Tahoe at all, let alone 26.4, if my workplace hadn't insisted on it.