Hi. Thank your for answer. In fact, I did a lot including your suggestions, reinstallation of the browsers, firewall issues etc, all I can imagine as an IT specialist. Then emailed LetsEncryt support enclosed above::
Dear Sir/Madame,
I'm writing you from Turkey, my name is Safak Kayhan, related to a difficulty I experienced during my latest visits to some websites which are using LetsEncrypt certificatiion for their SSL certification.
I first noticed this issue yesterday when I revisit https://lichess.org. Then today same issue appeared for https://support.zyxel.eu. Finally I checked for one more EU originated website
which I use occasionally https://geizhalz.eu With the browsers which use Microsoft certification utility such as Opera, Chrome and MS IExplorer this problem is 100% reproducable at my laptop computer (not others).
Finally when I couldn't solve the problem, I bypassed it and reinstalled Mozilla Firefox which uses it's own SSL method for certification process to connect above mentionned websites.
Thinking that this may be related with a malicious attack to my computer and might pose potential danger for other users as well in future, I prefered to inform you.
A solution would be great but a precaution seems just appropriate.
With my kind regards.
Safak Kayhan
PS1: The error message on Opera browser:
Your clock is ahead
A private connection to lichess.org can't be established because your computer's date and time (Friday, October 1, 2021 at 8:30:39 AM) are incorrect.
NET::ERR_CERT_DATE_INVALID
PS2: I erased Let's Encrypt certificate from Microsoft certificaiton utility to overcome the problem. How can I restore or install it back without opening MS update service. Thank you.
No support available answer suggested this silent forum. Thanks anyway.
Regards.
Safak