1080p too much?

The very first Raspberry Pi can already play 1080p video pretty good.

Got a full debug log for us via pastebin?

Quote from blueribb

HEVC (H.265) files require more horsepower to play. Stay away from these files with a RPi

blueribb is correct - there is no way the RPi3 can normally play HEVC at 1080p. Maybe the RPI3B+ might be able to but I haven't tried. I tried a milhouse build on a normal RPi3 which had a few tweaks and seemed to work at 720p.

Easiest way is to use "Handbrake" to convert to X264 - although not on a Pi unless you have a few weeks to spare

Milhouse builds (Kodi Leia) do a pretty good job with HEVC 1080p videos on a RPi2/3/b+. Obviously not the very high bitrate videos, but the usual rips video have a good track record.

Quote from jglazer63

have a good solution specific to pi

use milhouse builds the latest Kodi18 builds have several improvements at the HEVC department

A quick search shows many examples. This should work on a Pi.

INPUT="$1"
for i in *.mkv ; do
    ffmpeg -i "$i" -bsf:v h264_mp4toannexb -sn -map 0:0 -map 0:1 -vcodec libx264 "$i.ts"
    mv "$i.ts" "$i.mpg"
    sleep 3
done

From Here

You may have a look into emby at your NAS and "emby for kodi" for your Clients, that superseedes the MYSQL shared db by ages (incl the possibility to transcode).

it doesn't replace it, it basically supersedes it.

Emby in general is something like Plex (just free), there you can add multible users, age limits etc ... with the Emby for Kodi Addon you can "grab" that db and use it natively at Kodi. It also supports transcoding for usage over the internet/wlan etc ...