Reminds me of a similar story from a colleague regarding email an email that couldn't be sent with a specific subject. After much troubleshooting by L1/L2 techs it turned out to be a bit pattern error / broken ASIC in a core router/switch.

I've personally twice encountered similar issues, once with FTPS and another with HTTPS, both manifesting as strange cryptographic failures, but ultimately caused by broken network device somewhere in the path.