Don't nuke the CUPS certificate
CUPS is Apple's print server setup. It is essentially a tangled set of web services and these days, encryption is enabled by default. Kill the cert and your printer may stop talking to you.
Self-signed means the cert isn't trusted beyond the local computer. That is fine for the use CUPS puts it to.
c-73-158-167-161.hsd1.ca.comcast.net is the Comcast hostname for a residential (dynamic) IP address (73.158.167.161). I can't say why Apple would have it in the keychain but if Comcast is your ISP, then it could be your cable modem.
TPM draws a "Connection not secure" error because the protected page contains unprotected links. That complaint is genuine, it is not due to a certificate problem.
If all else fails and the problem persists, you can manually download and install the cert chain from Sectigo (although, based on your adventures further down, you may have to override Safari's error dialogs.)
Self-signed means the cert isn't trusted beyond the local computer. That is fine for the use CUPS puts it to.
c-73-158-167-161.hsd1.ca.comcast.net is the Comcast hostname for a residential (dynamic) IP address (73.158.167.161). I can't say why Apple would have it in the keychain but if Comcast is your ISP, then it could be your cable modem.
TPM draws a "Connection not secure" error because the protected page contains unprotected links. That complaint is genuine, it is not due to a certificate problem.
If all else fails and the problem persists, you can manually download and install the cert chain from Sectigo (although, based on your adventures further down, you may have to override Safari's error dialogs.)
