I am running kodi 18 and IPTV perfectly fine. Very stable combination. So are other people around me. Very hard to guess what is causing your issues. I would try another piece of hardware if you are having this issues with the same hardware. You can run it on cheap Chinese hardware boxes where...
I have the same problem as well on Kodi. the last couple of weeks I can hardly start a channel stream. While inside my smart TV it is working as expected.