The PDM server has some issues with licensing once its been restored. 

Once its been restored from backup the license manager is broken. to fix it do the following:

Open the Solidworks 2018 licensing manger:

1: Select Move to a new or upgraded computer

2: Confirm license server information, though it should be right.

2.5: if it failes, answer "yes" to the activation wizard. then go through all that again. it should work