Remote user access on Samsung Smart TV constantly buffering on video playback

Server Version : 1.42.2.10156 (Western Digital My Cloud Home)
Player Version : 5.93.2, Platform 8 (Samsung TV)
My friend used to have no problems at all, then the Plex app on his Samsung Smart TV updated late last summer and he is constantly getting freezes, then buffering, then video plays for maybe 20 seconds then buffers again and this cycle makes everything unwatchable. His access to our WD Plex installation works fine on his mobile phone and iPad (using the same wi-fi connection). He has uninstalled and reinstalled twice on his TV and it has made no difference. There seems to be a problem specifically with the TV app. What else can he do, as he is clearly getting through to my Plex okay on other devices using the exact same route in, so I don’t think I need to change any settings at my end. Any tips gratefully received!

Do I assume that not everyone who has a Samsung TV and the Tizen OS Plex app has problems with remote playback? My friend is still having issues with video (music is fine). We have two Samsung TVs and they both access video fine, but then we aren’t doing it remotely. Are there any settings my friend can check or change?