You can download the update file from ipcamtalk's archive and install it manually: Blue Iris Software Updates
Also, ironically UI3's new update check function still works even while Blue Iris's official method is down, because UI3 does its update check through a third party cloud server (biupdatehelper.hopto.org which I own and operate). That server happens to be caching the latest update check data it got from Blue Iris's infrastructure before their database went offline. So you can use that if you have UI3-334 already (or manually install it). It is in UI3's main menu > Server Control > Check for Updates. The update check will fail the first time; just click the button "Check Using Third-Party Service". I'm in the process of redesigning this whole update check UI flow (I think everyone can agree it is rather buried right now) but in its current state it at least works.
Also, ironically UI3's new update check function still works even while Blue Iris's official method is down, because UI3 does its update check through a third party cloud server (biupdatehelper.hopto.org which I own and operate). That server happens to be caching the latest update check data it got from Blue Iris's infrastructure before their database went offline. So you can use that if you have UI3-334 already (or manually install it). It is in UI3's main menu > Server Control > Check for Updates. The update check will fail the first time; just click the button "Check Using Third-Party Service". I'm in the process of redesigning this whole update check UI flow (I think everyone can agree it is rather buried right now) but in its current state it at least works.