Got pretty much the same symptoms over here.
I rolled back to the Emby for Kodi plug-in from the stable repo (4.0.5) by deinstalling beta (4.0.23a) and installing 4.0.5.
Connection problem solved.
Just for info (maybe it helps):
Problems with connection loss to the server occured after updating from CE 9.0.1 stable to a CE nightly build (i guess, but am not totally sure - from Kodi 18.1 to 18.2). Before that, 4.0.23a worked fine.
I can easily re-adjust an error situation anytime by installing the 4.0.23a plugin again: Instant error message with referral to the log (which I did not check yet, sorry!). Did not check either, if the server loses connection than.
Edited by hi2hello, 15 May 2019 - 05:46 PM.