Steven Zahm@ Andy
SiteShot uses a service provided by wp.org called mshot in order to create the site screenshots. It is pretty much a block box to which I have not direct control over…
For sites where you are seeing the 503… my best guess is the site’s server firewall is blocking access, In the past I’ve tried other services which provide site screenshots, they too would also receive same message. So this leads me to believe that it is not the service but the site.
They may not purposefully be blocking, but they could be blocking something else which has the side effect of blocking these services.
The only real solution here is to take the screen capture yourself and add it to the entry.
In regards to the 404 message. I’ve seen this when the site being captured is too slow in responding or unresponsive at the time of being captured. The captures are cached by mshot for a period of time and that cache can not be flushed.
You will also get 404 when trying to capture a site with an incorrect or a redirected URL.
For example on this page https://www.storrington.org.uk/attractions/food-and-drink/ the entry for The Moon Pub. The website is http://www.themoonpub.co.uk/ but it seems that URL is actually redirected to https://themoonpub.co.uk/. Notice the difference? Try correcting the link to see if that fixes that entry. Keep in mind the captures are cached are it will take time for that cached capture to be refreshed.
Hope this helps. Let me know.