My router that my isp provided me cant go over around 30 down and 5 up

[MartinsA]

My isp gave me the Nighthawk R7850 router and we were told that we should use that router. were paying for 400mbs but for some reason the speeds cant go faster than 36down and 5up. ive tried every troubleshooting step like restarting turning of stuff like QoS and factory resetting the router. is there any way to fix this.

Heres a below screenshot of the speeds

[plemans]

What modem/gateway do you have? 

Are you speedtesting wired? Wireless (and if wireless over 2.4ghz or 5ghz)?

What firmware is on the router? 

[MartinsA]

the modem that i have is provided by spectrum and its a e31utv1

im speedtesting wireless and the 5g and 2.4g results are the same

the firmware is V1.0.5.68_10.1.75

[plemans]

What speeds do you get hardwired into the router? 

And what results hardwired into the modem?
what device are you using for speedtesting? 

And what app are you using for speedtesting?

[MartinsA]

i get 30 when im wired into the router and around 400 when iim wired into the modem

im using my personal desktop and speedtest by ookla 

[plemans]

Have you tried downgrading the firmware a verson, then doing a factory reset, and a clean install? (by clean I mean, don't use a backup configuration)