Software center won't display

Neither the available nor the installed tabs on the software center will display information. The screen updating circles go round and round, then they finally stop and the screen is blank, except for … in the center. Content displayed here when I built the system, and at some point afterwards, but now nothing. Any ideas what might keep the list from updating?

This is on a server working as a gateway that seems to be performing fine in every other respect. Thanks.

It has happened to me yesterday which I posted on support section. Pls see my section:

I think it has something to do with the network…either your network/internet connection is slow or the repositories are. Right now, going into 2 hrs after 2 hours after clicking on some modules to install, I’m still at 7%.

Hope you give it more time to connect and collect everything it needs.

Duplicate, please @AZChas continue on the the topic suggested by @vhinzsanchez