Network speed at Amazon Firestick

I purchase "up to" 175 mbps from Xfinity. I use a Netgear N600, model C3700. I measured about 24 mbps using fast.com, but only 8 mbps at my 1st generation Firestick. I also use Bitdefender VPN. Don't know what additional information would be relevant. Would you please make some suggestions (the most effective first) as to how I increase my speed at my Firestick? Thanks, in advance, for your help.