If you receive an error saying something like "Connection is insecure" while accessing your LMS from your work / institution computer but you can get to it just fine from home or using a recent mobile device using mobile data, a possibility is outdated LetsEncrypt root security certificate on your organisation's device.


Try accessing the site from your phone or a non-corporate computer.


The corporate devices may have not received the correct updated LetsEncrypt root certificate because the devices automatic certificate system update is broken or disabled by policy. There was a major rollout of root certificates by LetsEncrypt 30/09/2021.

If your device is unable to verify the certificate chain it will find a certificate that will complete based on the root certificates available on your device and report an incorrect certificate for the domain.


Please refer your IT department and refer them a search like this one:

(https://www.google.com/search?q=windows+2021+verify+letsencrypt+root+certificates)


e.g.

https://techcrunch.com/2021/09/21/lets-encrypt-root-expiry/

https://community.spiceworks.com/topic/2333959-letsencrypt-r3-ca-expiration
https://aboutssl.org/how-to-tackle-wrong-or-invalid-ssl-certificate-error/


Or go here and try it on several devices. It will possibly fail on your work supplied device.
https://valid-isrgrootx1.letsencrypt.org/


A more advanced test is to see if the new root certificate is installed on your Windows PC.
On Windows
Click start
Type in certlm.msc and accept the elevated privileges prompt.
Select Trusted Root Certification Authorities
Then Certificates
If you don't see ISRG Root X1 then the device certificate update service is broken.