Well, at least you can play with cache readfactor in the file /usr/share/kodi/system/advancedsettings.xml which is 5 at the moment. Perhaps you can get some improvement by this since you’re now using a gigabit adapter with more bandwidth than the built-in interface of the Vero 4k for which the current value is designed and tested.
https://kodi.wiki/view/HOW-TO%3AModify_the_video_cache
Addition: Please, don’t change the original file /usr/share/kodi/system/advancedsettings.xml but use /home/osmc/.kodi/userdata/advancedsettings.xml to make changes persistent against updates.