UNC Path fails by IP "no network provider accepted the given network path", but works using hostname

Solution 1:

ok it would appear the problem is resolved after uninstalling KB968389 (ref) and then reinstalling again. this has had me stumped for a few months, i would never have guessed it was NTLM related...

to quote:

If you capture network traces while trying to access shared folders, you may see a response of Error, Code =(13) STATUS_INVALID_PARAMETER from the server for the session setup:

192.168.0.2 192.168.0.1 SMB:C; Session Setup Andx, NTLM AUTHENTICATE MESSAGE, Workstation: WRK001

192.168.0.1 192.168.0.2 SMB:R; Session Setup Andx - NT Status: System - Error, Code = (13) STATUS_INVALID_PARAMETER

This error code means that there is an issue with NTLM authentication. The update in KB 968389 introduces a new feature that enhances protection and handling of credentials when authenticating network connections by using Integrated Windows Authentication.

This behavior can occur if the update discussed in KB 968389 did not install properly. To correct the issue, please uninstall the update completely and then reboot the server. After the restart, you should find that the symptoms no longer occur. Reinstall the update from KB 968389 and restart the server again. The issue should not re-occur. You should be able to access all shares successfully locally and remotely.