One of my users is reporting an inability to connect to ircs://testnet.ergo.chat:6697/ with mIRC v7.66. They report that initially they were able to connect, but then a subsequent connection attempt failed. This suggests a possible issue with STS, since the server publishes the following STS token in its CAP LS 302 output: "sts=duration=86400,port=6697".
Here's the client configuration: https://i.imgur.com/EaM0yu8.png
The error is: "[05:24pm] * Unable to connect to server (SSL certificate verify failed)". (The time is 5:24 PM PDT [UTC-7] on September 29th, 2021.)
Here is the current certificate chain we are serving: https://gist.github.com/slingamn/ac339674da32ff086a2d17250f32854c
Thanks very much for your time.