I have a Mifi dongle (mobile wireless broadband). I have had it nearly a year now with very few issues. I have bought a Nexus 7 and have found that my internet connection is pretty poor. I thought it might be the Mifi so I tried running the Nexus off my HTC One X (wifi hotspot). It struggled with this as well. I am not sure if it's the network or the device.
Any suggestions would be welcome as to what I can do.