Allworx internet based work phone times out

My wife's company supplies her an Allworx internet based phone to work from home. When it first boots up it will work for only a couple of minutes, then it will stop receiving and sending calls, yet it continues to have a dial tone. Other employees use hotspots from other cellular companies with no issues. We have the ATT netgear nighthawk. Nighthawk signal is received by a bridge that adapts it to ethernet cable for the phone to plug in. Any help is appreciated.