tl;dr: My ISP’s CGNAT session timeout is too short, meaning TCP keepalives gets dropped. Test if your own NAT, or your ISP’s CGN, violates RFC5382‘s REQ-5 using this tool: https://github.com/AndersTrier/NAT-TCP-test. I have been working from home more lately, where I have SSH sessions open to the servers that I’m working on. Often when I return … Continue reading My ISP Is Killing My Idle SSH Sessions. Yours Might Be Too.