Re: mbps drop
Post your modem stats and info so we can tell if it's been updated or not.
If it's been updated then it's supposed to make the connection more reliable, not less. If it's not been updated, then it could conceivably be the Superhub detecting interference and automatically downgrading to avoid both causing and receiving said interference. Although as far as I know that functionality on the Superhub is deliberately faulty or disabled.
Ultimate® SuperHub2™ Mod©:
N750 Simultaneous dual-band wireless (300+450)
5 Upgradeable antennas, dual-processor, 7 ports
Fully customizeable dd-wrt/openwrt routing engine