Hmm, ESET is intercepting connections on a custom port but not on port 443? Is that a setting in the ESET control panel, because normally they intercept both 80 and 443 by default. I hadn't thought about other ports. I guess my inclination would be to suggest to temporary turn off ESET scanning your web connections. This article should help with that: [[How to troubleshoot security error codes on secure websites]].