Here in Rawalpindi, I'm facing a similar issue,
The modem takes anywhere from 3-8 minutes to 'sync' ... sometimes ALL the green lights are on yet it takes another 4,5 minutes until sites starts opening (before that , they keep time outing on me).
I've checked its not the router but the Modem/ PTCL end problem.
Tried both static and auotmatic DNS server assignment (in ZTE modem settings), seems like recenlty PTCL effed something up in the exchange or elsewhere.
16:09 Abbas- • wtf is wrong with ptcl
16:09 Abbas- • restart modem
16:09 Abbas- • takes 4,5 mins for LED lights to show connected status
16:09 Abbas- • after taht u do http://i.imgur.com/TrWIv.jpg
16:10 Abbas- • and then it takes another 3,4 mins before you are 'actually' connected and can browse and tracert anywhere. something is wrnog with ptcl.