This certificate was signed by an untrusted issuer

Lately I have been receiving that error message when attempting to connect to several different servers, including my own VPS server. The common factor is they are all servers that have certs issued by Comodo.

Windows and Android users can connect to the servers just fine. Both Comodo and my ISP have independently verified that the cert is installed correctly.

I am having this problem not only with multiple Macs and iPhones in my household, but also with multiple clients's Macs and iOS devices.

Any one else start having this problem recently?