Cannot get replacement wireless routers to connect to internet

I am trying to replace my old wireless router (a 12-year old Rangemax WPN824 v2) because that router caps my download speed at ~20Mbps.  That wireless network originally used WPA2 security with an access list for all peripherals connected to it.  I am trying two different routers as replacement options for that Rangemax - one is the WNR3500 -- the other is an older Netgear, a Wireless N-150/WNR 1000 v2).  I have performed factory resets for both as they were used by prior owners.  After the resets I cannot get either router to make a connection with the internet when the WAN port is connected to the ethernet and my old router is completely disconnected.  I do have inernet from my source modem just fine - I can see bth routers on the list of available networks, but no internet can be connected.  Any pointers would be very much appreciated.  I can't help but think this is some lingering issue with using MAC address access listing from my prior network, but why wouldn't an internet connection be secured between router and cable modem after reset? My ISP confirmed they have nothing to do with allowing independent routers on the network.