After the upgrade to 1 Mbps standard, there is no stability in the network too. The modem shows connected, all parameters are apparently normal but there is no data transfer. After few seconds upto minutes data connectivity resumes by itself. And the speed keeps varying while earlier it was rock steady.
May be their network is indeed overloaded at the local level. Also could be bad optimization or something at the back end.
This is supposed to be their New Generation Network that can handle much more.