However, the AGPtEK USB HDMI KVM Extender Over Ethernet adapter I'm using to remotely control the CCTV DVR from my desk (HDMI and Mouse control) seems to be much more robust, and has held up fine.
Checking AGPtEK's website, I discovered they make HDMI extenders of their own, likely using the same chipset, AND they have another really nice feature: you only need ONE transmitter (the J-Tech system needed a transmitter and receiver pair for each HDTV). The one transmitter can go through a standard switch - either your existing network switch or it's own dedicated switch off the main network (gigabit recommended). Since I wanted to keep things isolated, I just used a dedicated 5 port gigabit switch to connect the transmitter to the four receivers. This greatly simplifies things, requiring a lot less hardware and wiring in the utility closet.
AGPtek LKV373A 365ft/120M HDMI Extender over LAN Routers/Switchers Ethernet Network RJ45 CAT5 CAT6-Single Source from 1080P Full HD:
https://www.amazon.com/dp/B00TO8SX7G/re ... UTF8&psc=1
The HDMI over Ethernet stuff was just lying on the top shelf in a messy pile while I was testing it, but now that I seem to have a reliable system I went ahead and mounted everything to the board in the utility closet, to make everything look neat. The HDMI over Ethernet stuff is on the right:
![Image](http://soldcentralfl.com/bob/utility_closet070717.jpg)
This is the manufacturer's diagram showing the installation option I'm using with a dedicated switch:
![Image](https://images-na.ssl-images-amazon.com/images/I/61EhW0y4q5L._SL1000_.jpg)