I have a solution that is now working for me.
I finally learned how “Adjust automatically” and “Home streaming” work together and that got me there.
The main problem was that I was attempting to use reasonable values for “Home streaming” and could never get both 1080i and 720p TV content to start under H264 transcoding. This also kept me from seeing how “Adjust automatically” works.
The key for me was to pick an unreasonable value of “1.5 Mbps, 480p” for “Home streaming” . This forces both 1080i and 720p TV content to start transcoded into H264.
With that solved, “Adjust automatically” set to on quickly causes the bitrate and resolution to be negotiated up to what your network connection can support.
No more MPEG Direct Stream/Play related crashing in the Plex app. So far no amount of FF/REV skipping has caused an app crash for me.
The negotiation will honor your “Limit remote stream bitrate” server setting in “Remote Access”.
The in-player quality settings don’t reflect the current negotiated resolution and bitrate. They simply show the unreasonable 480p value.
The Dashboard will show the current elevated H264 bitrate but does not seem to indicate the current resolution for me.
I hope this is a general solution for all.
P.S.
I still have “Enable I/O cache” set to OFF. I may test if that makes a difference sometime later but for now i’m just leaving that alone.