MathHub.info is currently experiencing technical difficulties. We are working hard on restoring the service, but without the drupal-based front-end this time (it is just too heavyweight and attack-prone).
For the MathHub MMT server, please use https://mmt.mathhub.info/.
For the Theory Graph Viewer, please use https://mmt.mathhub.info/graphs/tgview.html.
The MathHub Archives can be found on https://gl.mathhub.info/.
Finally, the development server (preview of what is to come) can be found at https://new.mathhub.info