Comodo SSL when you buy their cheep SSL package, gives you three CA bundle files that have to be installed in the right order. If not put in a certain order, the cert won’t work.
The order is:
I have a command that will allow you to install them to a new file you can then rename as needed with them installed in the right order.
cat COMODORSADomainValidationSecureServerCA.crt COMODORSAAddTrustCA.crt AddTrustExternalCARoot.crt > whole.comodo.ca.cert