I too got the "No UDP data" warning, but my Fireface UCX still connected. HOWEVER, it cycled through "connected" and "offline" every 5 seconds (upper right indicator on iPad's TM Remote). Thus, of course, the two interfaces only came into sync every 5 seconds. FYI my systems: MacBook Pro 15-inch 2017 touchbar, MacOS High Sierra; iPad mini v4, iOS 12.1—TM Remote 1.14, TM FX 1.50.
Obviously on the same WiFi network, but, in checking, I discovered that I had two network interfaces active (Ethernet AND WiFi, albeit different IPs). When I unplugged the ethernet cable my TM Remote became rock solid.
Hopefully this will help someone else troubleshoot a similar situation.