I have ATT Fiber and I set my router so that WIfi is turned off and set to bridge mode. My m5 is in router mode. I have the main m5 connected to the ATT box and it gets a 172 ipaddress.  The rest of the network runs in default m5 settings.  Wireless seems to be working as expected. When I connect a computer directly to the 2nd port of the main m5 I get slower than expected speeds.  When I connect the computer to the ATT router and it gets a 172 address like the main m5 does my speed goes to exactly what I expect it to be.  I am using iperf3 to a webserver that is currently not used much that I have at bluehost. I get 440 Mbps when I connect to the 2nd port of the main m5.  I get over 900 Mbps when I connect to the ATT router.  I tunred off all the antivirus stuff and that has improved things and is what got it up to 440 Mbps. It was slower before that. I also tried dissconnecting all devices except the computer to see if that was it. I am the only one in the house using the internet. I have moved the cable back and fourth between the m5 2nd port and the ATT router sevearl times and it is very consistent. I'm sure putting it in AP mode will fix the problem but I would hate to have to do that.