I also got sometimes intermittent connection issues. phone says its connected with H but when you browse the net, there's nothing.
But it's hard to determine if its starhub's problem or the phone's problem...
maybe changing to an actual micro sim card might help?
I thought that was the issue too so went to get a brand new micro sim from Starhub. It did not resolve the issue. There's definitely compatibility issue on 3G between N4 and Starhub's network unfortunately.