Orbi 20 Certificate is conflicts with my own certificate

I am running my own server in the house. Therefore I forward ports 80 and 443 to 192.168.1.100 (at a fixed address) where my server sits. My server runs a Letsencript certificate which gets automatically updated every three months.

There are two Windows PC's, two phones and two tablets using this server for files, addressbooks and appointments. Very nice everything private.

What I did not expect is that Orbi has a certificate (that I do not seem to be able to switch off) which is presented to my six devices instead of the certificate of my server. I have switched off secure https but the Netgear certificate does not go away.

Now, after reading all messages on this forum, I see that the Netgear certificate is a common problem. What is difficult to understand for me is if I approve the Netgear certificate as well on my devices does this give a security breach?

Thank you for helping me out on this issue.