Here is our new FAQ entry that explains more about timeouts.
Question: Why I see Timeout status on some links sometimes, and the same links work in another case?
Answer: Timeout status means, that the request to check link's validity timed out, meaning the remote server did not reply in time. This can happen, when, for example, the remote server is down for some time. It also can be due to the fact, that links are checked "quickly" when the user posts them, with 0.5-second timeout, but the links are scheduled for more thorough check, with 5 seconds timeout, via a deferred task. So, you may see a link as invalid right after posting, but after some time, if the link is valid, it will turn to valid status.
Some remote servers prefer not to send 403 Forbidden error when the access to some resource is denied (e.g. you IP is blocked on their server), but to block the request by keeping it open long time and eventually timing out. In this case you will get permanent timeout status even if you re-check the link.
Rebuild Data admin page also allows to manually set the number of seconds for a request to timeout. If you see too many timeout errors, you should consider to increase this limit. We have also implemented the option to check only timed-out links, so we would recommend to check all your links with normal timeout limit (1 second), and only after that check the links that timed-out with higher timeout limit (e.g. 5 seconds).
Please note, that timeout error is a connectivity issue and not a bug in the product, and if the same link times out one time and not another time with all other conditions being equal, that does not mean the product works differently each time, but that the link is available for not at that moment.
@Nirjonadda we will contact you in our ticket system about your links in particular.
Thank you!