@sesantanajr 

Hello, are there any QoS settings on the C7 for some specific devices? Disable it, or reset the C7 to factory defaults then reconfigure it from scratch, connect these 5G clients to the 5G network again to confirm if the speed is normal.

Please check the link speed on the client devices when they connect to the 5G network if the speed is still abnormal, show us the screenshots, thanks.

BTW, what are the 5G devices? What is the distance between these client devices and the C7 router? What if you move closer?

Try modifying the 5G wireless settings on the C7, such as wireless channel and channel width? It is suggested to run a Wi-Fi analyzer to find a clear 5G channel, then change the channel width to 80MHz, reboot the router and reconnect to the wireless network, then confirm.