Connection to site isn't secure

I am unable to access https://mychartor.providence.org/mychart/ site. It shows "connection to this site is not secure". If I change the dns to 8.8.8.8 on my laptop or phone network configuration, it does work. Also I don't have this issue with any other sites.

Any idea how to troubleshoot this to fix it?

root@43e590684d0b:/# host mychartor.providence.org localhost
Using domain server:
Name: localhost
Address: 127.0.0.1#53
Aliases: 

mychartor.providence.org is an alias for mychartor.glbpres.providence.org.
mychartor.glbpres.providence.org has address 170.173.10.63
root@43e590684d0b:/# echo | openssl s_client -connect mychart.providence.org:443 2>/dev/null | openssl x509 -text
unable to load certificate
140065633132608:error:0906D06C:PEM routines:PEM_read_bio:no start line:../crypto/pem/pem_lib.c:686:Expecting: TRUSTED CERTIFICATE```