Why does my phone take a while to connect to 4G?

[AC Question]

Hi,
I have just purchased a refurbished Samsung Galaxy S5 after my old one broke however I am having a little trouble with my 4G connection.

When I re-boot the phone or disconnect from wifi the phone automatically connects to H+ or 3G, I eventually get a 4G connection however it takes about 10 minutes. On my previous S5 it connected instantly.

It is android version 5.0, and the network mode is set to 2G/3G/4G (auto connect) in mobile networks. My operator is GiffGaff who piggyback on the O2 network.

Does anybody have any idea what could be wrong?

Thanks

 

[B. Diddy]

Welcome to Android Central! What's the exact model number of the phone? It's possible that the LTE bands it supports doesn't overlap much with GiffGaff, and the LTE band that is finally connecting might be a weak one.