Windows: remote playback through reverse proxy stops video randomly

[zedalert]

Test environment

PMS Version: beta 1.25.1.5286 (and also on previous beta versions starting from 1.25.0)
PMP Version: 1.38.0.2734
Platfororm: Windows

Steps to reproduce

1. Publish remote access to the server through reverse proxy and custom URL with both local and remote links
2. Play video from the remote network with PMP

Current behavior

1. After 5-10 minutes of the playback video unexpectedly stopped
2. PMP doesn't show the correct watched timeline (like it has never been watched)
3. PMP won't continue playback from the previous point and won't allow fast forward to any point

Expected behavior

1. Normal playback

At the same time accessing PMS remotely by the direct link that's published in the custom URL settings doesn't produce the same behaviour, everything is playing as expected. After random stop of video in the PMS at the same time in the web version of the player I see the correct watched timeline. Pressing F5 in the PMS doesn't resolve the issue with the timeline. Videos played in the local network with PMP are without any issues.