For no apparent reason my 6620L has started dropping connected devices and then the SSID name does not broadcast and I cannot get reconnected until I shut it off and turn it back on. I have done a factory reset but it continues to do the same thing.
You may have to contact VZW for warranty support on this one.
To help speed along any replacement or repair requests it would be helpful to know if multiple devices are failing to see the SSID or not when this situation occurs. Otherwise VZW may suggest that a single device is having a problem and it may not be their concern.
You did mention a factory reset which is a good troubleshooting step in this scenario. However you should clarify if you attempted using the Restore Defaults option from the control panel or used the "Master Reset Button" under the back cover near the battery. These button related resets typically go a little farther than the resets offered from the admin page or the control panel and should be attempted before contacting VZW for warranty support.
I will try warranty if I can figure out how to contact them. I am seeing multiple devices fail, iPad, iPhone, MS Surface & a Macbook.
I did a master reset with the little button on the back, i will try it from the admin page as well.
That should be all the confirmation they need to send you a replacement. That device does not appear to be operating as intended. Share with them what you shared here and you should get a new one in no time.