I recently upgraded to 1 Gbps service on Comcast but cannot get over 300 Mbps on my Samsung Galaxy S9+ or my laptop using a Killer Wireless 1435 NIC. I sometimes test under 200 Mbps at speedtest.xfinity.com. It doesn't seem to matter if I connect (5 Ghz specifically) to my Nighthawk R7000 or the modem / router gateway they provided. I split the signal on both to be sure I was connecting 5 GHZ. The S9+ and Killer Wireless 1435 are both rated for over 1 Gbps.