Altiris 7.5 agent unable to register to NS

Hello All , 

Few clients in my network are unable to connect to NS and register while connected using wifi after upgrade to 7.5 SP1

I have to connect them to LAN register it with NS and then it works on Wireless connection

We use SSL connection and these are not CEM clients 

Checked with firewall and ports and was unable to find any errors.

Please help 

SVR