DNS Dropping

I have had two WAC510 access points hard wired to my ATT Uverse Router working relatively well for a few months.  I decided to purchase a third WAC510 AP to eliminate WIFI frequency conflicts between the ATT and the Netgear.  When I installed the third WAC510 it worked intermittently and continued to lose internet for the home network inluding direct wired desktops.  Seems like the DNS is being dropped constantly.  Restarting router and AP's only fixed issues temporarily.