Download "ISRG Root X1 (isrgrootx1.der) file" from https://letsencrypt.org/certs/isrgrootx1.der to C:\windows\System32 folder
Run Below command as administrator
certutil -addstore Root isrgrootx1.der
Refer https://community.letsencrypt.org/t/windows-7-chrome-net-err-cert-date-invalid/161246/28 for more details