My wifes' 2007 iMac WIFI 802.11n won't stay connected. My 2014 iMac 802.11 a/c is in the same room about 2 feet farther away from the modem and I get 30-35 Mbps download to her 2.5Mbps. She is about 60 feet from the modem. We connect to 5G network. Do we upgrade her card or do we buy a booster or ...???