On 3G or 4G, you may need to try different Port settings if you have trouble connecting.
In Photon : First try "Gear Icon" -> Port and switch it to 3. Press lightning bolt. Does it work?
Next, please try the other Ports such as 4, 1 and then 2. Most of the time, Port 3 and 4 would work for most connections.
If it still did not work, it is likely that you have insufficient network coverage. Please move into an area with better network coverage or use Photon over a high-speed wifi service.