For over 2 years I used a Verizon UM175 3G modem for my internet connections...No problems,a bit slow but solid as a rock. About a year ago 4G became available in my area so I upgraded to the 4G 551L. BIG MISTAKE! Although I've installed the latest firmware (I had to bring it to the local Verizon store because my internet connection is not sufficiently reliable to perform lengthy downloads) the 551L has been nothing but trouble. I have it forced to EVDO (3G) only, I have purchased and installed the recommended aux. antenna, and I have it configured to the most reliable settings (as recommended by Verizon tech support), but this modem WILL NOT MAINTAIN A RELIABLE CONNECTION! I've contacted Verizon tech support, Verizon customer support and brought the unit to my local Verizon phone store. NO HELP FROM VERIZON! Unfortunately, because I live in a fairly remote area I have few other choices for internet connect. I've asked Verizon if I can downgrade to using my UM175 again and was told I can.... after my 551L contract expires, but the monthly fee for UM175 3G only will be $10.00 higher than for the 551L 4G service (go figure). I've written this out of pure frustration with Verizon and the 551L unit and maybe it will help someone else avoid the same situation. Am I the only one with 551L issues?