Unable to access Thingworx Server from PTC University

Hi,

I am a user of PTC university. I have been following the course 'IOT UI development with Thingworx' and have been accessing the thingworx platform using the URL provided for a while now and it has been working perfectly. However, since the week of Christmas 2019, whenever i try to access the platform i am displayed the message 'Server error. Please confirm, if your portal environment is running.' or an NGINX error is shown. 
The server URL is: ptcu-thingworx83-ui.portal.ptc.io 

Any advice to resolve this? 

Thanks.