I have the same unraid hardware as previously, but lately I cannot treak 4K videos (even occasionally 1080p) to Kodi without buffering.  I'm using Nvidia Shield TVs as front ends, have been using Kodi since XBMP, which have worked well in the past. Can you guys recommends a way to figure out if this is an unraid problem? BTW, this is all hard wired Cat6, and same wiring with previously no problems

If you have another computer available to help testing you can run iperf to test your lan bandwidth, use a single thread, if all is well it should max out gigabit, or be pretty close to max, and even 4k needs no where near that.