Try this if you can't get your remote working and you're using a Wifi Extender
After installing my new HTPC, I discovered that the Kodi remote app (on my Samsung GT-19070P) no longer worked. I'd get no connection or connection refused errors despite being attached to my wireless network and being able to connect to the Internet.
I tried everything from enabling/disabling UFW, opening/closing ports, rebuilding the host information, fixing the host's IP address, and rebooting the router. Nothing seemed to work. However, whilst rebooting my router via the web interface, I noticed that my phone didn't appear in the client list - hmmmmm.
I'd recently installed a wifi range extender in my lounge and my phone was connecting via this node: simply rebooting the device solved my problem and ended hours of frustration. I'm not entirely sure why the node was refusing to pass the datagram to the router, but it may have just been a glitch in the network layer. Anyway, the moral of the story; you can't reboot enough!
Sources & References:
- TP-Link: WPA281 Wifi Extender