License checkout failed. License Manager Error -9

Hi, I received the "License checkout failed. License Manager Error -9" error. I am using Xubuntu 16.04 and it has enp4s0 as network interface. I tried several times to reactivate license but always get the same "-9" error. I am under a student license with a course from University of Pennsylvania. Please help. What should I do? If you allow, I can uninstall it from this Xubuntu 16.04 and install it on another Ubuntu 14.04 which has "eth0" as network interface, hopefully that could solve the problem? Again, please help. Thanks. Best regards, Jianxin Liu