We've updated the external web location the game looks for mods to reflect a new home. The old home unfortunately went off line, and we've been creating a new location for mods to live in the meantime.
Mods should now be operational again in game, both in search mode and should download correctly.
The only practical issue is that the mod list may not be updated with such frequency any more - more like once a day, rather than the multiple-times-a-day as it was previously.
This is a temporary fix, but there will be a new release at some point in the relatively near future which consolidates all mod uploading and curation into one location. Watch this space!