Lync Client login Failer

I faced this issue 2 times before. After you deploy Lync Edge Server Role, you try to login form a computer with Windows XP or  Windows VISTA but you get a popup message saying “Cannot verify your Credentials”.

After some investigation, I found the solution and it’s working well with me.

It’s the NTLM Settings on Client machine. Lync and OCS is very particular about the NTLMv2 settings.

I edit below registry keys in client computer (may be need to restart) and it’s working well

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0]
“NtlmMinClientSec”=dword:20080000
“NtlmMinServerSec”=dword:20080000

Please check detailed article