I recently received the 551L modem and installed it with no problem. We are still on 3G at the moment. Unlike the older modem - I now experience periodic (daily) dropped signals. Contacted Verizon a week ago - still no response. What's up with this?
I'm not sure what you have already attempted to restore, but If you have not attempted this if you can try to uninstall the VZAccess Manager, reinstall, reactivate and retest. Also, if you can provide me your city/state/zip code. After your observation if you can let me know if you noticed a better connection and if not we can move forward. Thank you.