Error with Google Drive

Hi, I was wondering if someone could help.

I have OwnCloud running on ISPConfig (CentOS 7) with a "Let's Encrypt" Certificate, and it works perfectly with PC and Mobile clients alike.

However, when I try to use Google Drive as external storage, I get this error:

"Step 2 failed. Exception: Peer's Certificate has expired."

Apart from that, all goes well - the folder [for Google Drive] even appears in User's folders!

Can anybody help?

Many thanks in advance!