I have a KiWi Wifi and it used to work with my iPhone 4. I have iOS V6.1.3 and my phone finds the plx device. The laptimer does not find KiWi WiFi

When I try with my iPhone 5 it all works

The plan was to use the iPhone 4 as a dedicated Harry's Laptimer tool and I have the TomTom handle which it finds and work great with.
Any suggestions to what could be the problem?
All the best
9MRSCS