@rpach2301 

Have you tested with other phones to see if the same thing happens?

Try going into the QoS menu and setting the phone as a priority. If you already have devices set as priority, remove them.

@rpach2301 If you had a previous router then upgraded to this one then I would turn off your modem for a couple minutes and once it is fully rebooted and connected to your ISP then turn on the Wifi router and ensure it's fully functioning.  I would also get into your cell phone(s) you are having issues with and find RESET NETWORK SETTINGS and do such.  The only problem is having to reconnect to wireless printers, bluetooth connections, etc but it's fixed many issues of wifi connection dropping, calls dropping, etc but I have read dreadful things about selecting the QOS option because on this router you cannot really prioritize a certain function and only the device - I had a Netgear Nighthawk that I could actually put calls, streaming tv, etc at a higher priority for bandwith but this one is either all or nothing.  

Good luck