The computer does not accept SSL certificates - what should I do?

Question

Browsers

For the first time I encountered such a problem - some sites are not loaded. They say that the connection is not secure. Everything would be fine, but among the non-loading sites Pikabu and Rutreker, as well as my own project, where I know for sure that SSL is valid.

If we tell the browser that we are moving to an unsafe site at our own peril and risk, then simple sites like mine work fully. For example https://doit3d.ru/ or https://prom-kapital.ru/ But the same Pikabu and Rutracker are loaded like this, but without styles.

The problem with loading some sites, including those mentioned, arose the day before yesterday. But then the ERR_TIMED_OUT error just popped up. Actually, the third evening I'm already breaking my head. I tried all the solutions to this error offered by Google. It disappeared on its own and was replaced by a problem with the certificates of the sites where it popped up ..

The certificate is marked as invalid even by https://cps.letsencrypt.org . In all cases, it says that the certificate has not yet expired or has expired. Although actually indicated corresponds to the current date. I noticed that all sites found with allegedly invalid certificates have a certificate from letsencrypt. They have digicert and sectigo certificates that work normally.

The problem is local, only on one PC. There were thoughts that Comodo Firewall was naughty, it came to removal, but nothing has changed. Tried Chrome, Opera, Fox, Tor - all with the same sites. I checked it on the laptop - the same home network, the same chrome under my login - everything works fine. I looked at the certificates, the expiration dates are the same. But on the example of the same Peekaboo, the certification path is different. On the laptop where it works, the path starts with ISRG Root X1. On a PC where it does not work with DST Root CA X3. In both cases, R 3 is followed by the site itself.

Both devices are running "free" Win7 Ultimate.

Tell me where to dig, what to do? It would be nice if the sites loaded normally, if necessary, you can still ignore the lack of SSL, but working on a resource with unloaded styles is still a pleasure.

Answer 1

update windows root certificates

Answer 2

Is the time on the computer set correctly? Check this.