I have 400 Mbps with wireless router/modem but only getting 170. Help?

[cmaxie]

I have  AC1600 /wufu Cable Modem Router 802.11ac Dual Band Gigabit.  I had Spectrum come in and check the Mbps.  It is 400 going into the modem/router but in the house only getting 170.  The Spectrum repair guy was helping measuring the Mbps.  Something is wrong for it to slow down so dramatically.  Any ideas, suggestions or info to help with this frustrating probelm.  It impacts my laptop and iphone.  With the iphone, call are dropped or people cannot hear me.  Thank you, CM

[FURRYe38]

What CM model is your gateway modem? 

Be sure there are not coax cable line splitters between the ISP service box and the modem. 

Be sure your using RG6 coax cabling. 

[cmaxie]

Thank you for your answer.  I will check the cable to make sure no splitters.

cm

[FURRYe38]

What CM model is your gateway modem?