I've been using this MoFi 4G LTE router for many years now. Never had an issue with it running 24/7. It uses a 4G data micro SIM card provided by your network provider. You have 4-Ethernet ports available, though can add more routers/switches as needed?
I keep my PC/notebooks and smart TV connected via Ethernet, and use WiFi for tablets/smartphones. I also prefer Ethernet as the signal is more consistent, and not subject to additional radio interference associated with WiFi.
Writing this post with MoFi connected by Ethernet: