Invalid certificate for MB6800 modem!

I have a Motorola MB8600 modem, DOCSIS 3.1, gigabit Comcast service. I have not gone to the admin page for awhile, but today I did, at 192.168.100.1 - and on IE I get "Certificate Error", and on Safari I get "This connection is not private". On IE, I can actually log in anyway by going to the details and proceeding against its best wishes; on Safari, I took a picture of the certificate it is not happy with. Is there a way to fix this, I can't believe that the modem is outdated? Thanks!