I have found a repeatable path to make the Plex Media Server unstable.
Environment:
PMS: 1.7.4.4017
iOS Client: 4.14
Mac OS X: 10.11.6
iOS: 10.3.2
Tuner: HDHR4-2US (20170612beta1)
I open the iOS Plex Client. I start watching a live broadcasts. I click the menu on the lower right to bring up a list of other programs. Select another live broadcast to watch, but I get timeout errors. From this point on I have to restart the PMS to start using live broadcast or DVR recording functions again.