Unknown Service Class – SonicWALL Posted on by Webmaster IT Support Forum › Forums › Network & Firewall › SonicWALL › Troubleshooting › Unknown Service Class – SonicWALL Tagged: Unknown Service Class This topic contains 0 replies, has 1 voice, and was last updated by Webmaster 7 months ago. Author Posts November 20, 2017 at 3:19 pm #2273 WebmasterKeymaster When trying to configure NAT Policies on a SonicWALL, you get this error: Unknown service class This is because either: You are translating one port to more than one port, or vice versa – You must make a separate NAT Policy for each port you wish to translate; you can only translate one port into one other port. You are trying to translate a UDP port into a TCP port, or vice versa. Creating a NAT Policy in either of the above scenarios causes the Unknown service class error in SonicWALL. Author Posts You must be logged in to reply to this topic.