Streaming Comparisons between devices & apps

Can anyone advise on the following situation?

I have two devices, a Windows Surface Book, and an Amazon Fire 10. The Windows machine runs OpenPHT & the Plex Windows store app. The Fire tablet runs the Android Plex app, and the Plex add-on for Kodi.

My Plex server is based in New Zealand, and I am in UK. There is considerable latency of about 350ms. However, I can’t understand why I have such different streaming experiences depending on devices + app.

On the Windows Plex app, I cannot stream most videos at all, unless they are low quality SD videos. When I try to stream other videos at the lowest setting of 0.3 mbps, it simply stutters and cannot play (and the video is practically unwatchable at that quality anyway).

When I run OpenPHT I can play MOST videos by forcing transcoding to 0.720 mbps. Some of the higher quality videos do not play, but generally do when I downgrade the bandwidth to 0.320 mbps.

On the Fire tablet, I have the same experience with the Plex app. It simply cannot stream videos. However, the Kodi Plex add-on plays videos at 1 mbps NO PROBLEM.

Both devices are in the same place using WiFI, and both have wireless A/C interfaces.

My server is incredibly powerful, with a 10 core Intel processor, and 32gb ram. The video files are stored on Raid 0+1 SAS drives.

Back in New Zealand, streaming isn’t a problem, and I understand the effects of latency on my connection. But I can’t understand why different apps and devices have such different streaming experiences. Can anyone explain why OpenPHT and Kodi add-on allow me to stream at much higher quality than the official Plex apps?

Thanks,

I’m using all static Public and Private IPs, and Jumbo frames were disabled.

I disabled Remote Differential Compression and Auto-Tuning. It’s difficult to measure if there is any difference here, as the situation is the same as before.

I’m testing on a 720p MP4 H.264/AAC TV Show episode, and still observing the same situation. Windows OpenPHT & Android Kodi add-on will stream when transcoding to a bandwidth of 0.320 - 0.720 mbps, but Plex on the Windows & Android native OS’s cannot stream it even on the lowest possible settings.

If I run a speed test from my UK IP to the nearest server in New Zealand, I get a download bandwidth of 8mbps, and like I said the latency averages about 350ms.