Certificate error on El Capitan but not High Sierra
I have been having an ongoing issue with my online banking related to a certificate issued by fisglobal. This started about 2 years ago.
On my MacBook runing El Capitan, when accessing some pages of the bank website Safari and Chrome both give error messages that the certificate cannot be trusted. Firefox sometimes accepts the certificate, sometimes does not.
On my iMac running High Sierra, I do not have the issue in Safari (only browser I use).
So when paying my bills, sometimes I can do it from the laptop using Firefox and sometimes not. The only workaround is to use the iMac, either by screen sharing or going to the room where it is located (NOT my home office).
Both computers are at their final supported OSes, so I can't just update the laptop OS to fix the problem.
When I use Keychain Access to check my certificates, I do not even see a certificate for fisglobal on either machine. So the usual advice to delete the certificate and rebot to force a new one to be downloaded doesn't work...nothing to delete! I used to see the certificate, where did it go? Is there some secret method to show "hidden" certificates?
MacBook Pro 13", OS X 10.11