Rbr20 slow Wi-Fi

[Sally81]

I have an RBR20 with an Arris modem without a router built in. If I power cycle the RBR I will get speeds in the 100Mbps range similar to a hard wired speed test. However with 20 minutes after rebooting the speeds drop to the 20 Mbps range. I have the latest firmware and have done a complete re-setup a new system after hitting the reset button.

[plemans]

What arris modem is it? 

What firmware is on the router and the satellites? (actual number and not "the latest")

do all device drop speed, just wired device, just wireless device? 

Is it only the devices connected to the satellite? 

when it does drop down in speed, have you tried hardwiring a device into both the satellite and the router to test speeds hardwired? 

have you tried connecting a pc to the modem and running it for a period to see if it drops speeds?