Outage https://meta.miraheze.org/wiki/Special:IncidentReports/31 was caused by an old, expired root certificate. However, the modern fix was relying on the UserTrust RSA Certification Authority root for our services. For some reason, that doesn't work and instead we have to rely on the AAA Certificate Services root. AAA Certificate Services is considered a legacy implementation, thus I have the feeling something is incorrectly configured when it comes to root certificates.