Hi
The update sh404SEF 4, 4.24.1.4308 is not available on the download page?
It is available on that page, and I just tested that I can download it right now.
The link https://u1.weeblr.com/dist/sh404sef/full/com_sh404sef_4.24.1.4308_j3_full.zip results in "Page not found"?
Correct, this link will always return a 404 if you simply try to load it in your browser. It's only usable by the Joomla updater, after having provided an update key and having an active subscription.
I suspect your subscription has expired and you can't access the downloads for this reason. You can check the status of your subscription on the dashboard page, and you'll need an active subscription for the corresponding extension you want to use to download/update them.
Best regards
Yannick Gaultier
weeblr.com / @weeblr