LAN plugin works with 3, but with 1 not

[silber1]

I have a LAN with 4 pc and one NAS. My Samsung S10 is connected to the LAN by a Fritzbox.
The Total Commander LAN plugin works fine together with 3 pc and my NAS. I can read files and directories.

But my new HP notebook HP Pavilion Gaming Laptop 15-dkOxxx (192.168.178.87) can not communicate with my Samsung S10.
I always get these errors:

SMB2 CONNECT:failed to connect to/192.168.178.87 (port 445) from/192.168.178.31 (port 56712) ///LAN/N4 or

SMB2 CONNECT:failed to connect to /192.168.178.87 (port 445) from/192.168.178.31 (port 49056) ///LAN/N4 if connected by WLAN.

I think it is a matter of windows defender firewall in the HP notebook and missing ports?
Any advice is highly welcome.

[ghisler(Author)]

The errors shown by the plugin indicates that it couldn't even establish a low level connection to the PC (before the .

The Fritzbox has a feature called "client isolation" which causes clients not to see each other, but see the internet. Please check whether this is enabled.