Hello Max Du 

If Studio can be activated from the server than the license is correctly activated on the server. Just to be sure go on the licensing server > open Safenet License Manager (WlmAdmin) > expand Subnet Servers > expand your server name > expand Allow TQA 2019 and send me a screenshot.

Did something changed on your Network before this issue occurred? Please make sure that port UDP is open on the server and on the user machines and that the user machines can ping the server and vice-versa.

Thank you,

Sorin

Hi Sorin

Thanks for the reply, but the license server machine also stopped working just after my post. I got in touch with our firm's IT staff and they were able to follow to the second to last step, but couldn't see AllowTQA 2019 in the window.

The user machines can ping to the license server just fine and vice-versa. 

Hi Sorin

Thanks for the reply, but the license server machine also stopped working just after my post. I got in touch with our firm's IT staff and they were able to follow to the second to last step, but couldn't see AllowTQA 2019 in the window.

The user machines can ping to the license server just fine and vice-versa.