@embucfan 

There is a lot to unpack there.  When ever you upgrade your speed package, it may not always equate to faster speeds on wireless.  This is because there are several factors that have be accounted for.  For instance the 1st question is what type of ethernet connect your modem to your router?  If its only Cat 5 then you will never see speeds above 100 Mbps.  So you would need to replace it with CAT5E.  Next you need to make sure your modem is desiged for the new speed.  For instance if you are on Cable service and have a Docsis 3.0 modem, you will only see speeds up to 300 Mbps.  Even though the modem maybe able to handle more most ISPs limit these modems to 300 Mbps.  So in this case you would need a Docsis 3.1 modem to get the up to 1 Gbps speeds.  You also want to check what the LAN speed is to ensure that you are getting the full speed from the ISP. 

Next you need to look at what band you are connecting to.  2.4GHz goes further but is limited to 100 Mbps in most cases.  The theroretical maximum is 150 Mbps but no one lives in an ideal enviroment so the most people will likely see on 2.4 is 100 Mbps. So in this case then you need switch, if possible, to 5GHz,  

From there you have to look at the client capabilities.  Most clients are 1x1 configuration on the antenna on their network card so the theroetical max speed is 433 Mbps.  As new technology comes out such as WiFi 6 and WiFi 6E this may change but for AC adapter 1x1 is most common.  This would mean nothing you can do to improve the wireless speed beyond the max. Unless you find an external adapter like a USB that is 2x2 or 4x4 configuration.  

  @Carl Related question:  I connected my Deco W7200 to a multi-gig internet modem.  I am getting 770 Mbps download and 712 Mbps upload speeds from the W7200 wifi router standing ~6 feet away from the router with direct line of sight between the laptop and router.  My client is the latest Apple Macbook Pro with wifi 6.  I am using the Ethernet cable supplied with my W7200 router to connect my router to my modem. Any suggestions of how to improve my wifi connection speed to be over a gig? Does the Ethernet cable supplied with the router support multi-gig speeds? 

  @Walawala1 

So this is what I found online.

This shows the 2021 model is going to be a bit slower than the 2020 even though its WiFi 6.   It also doesn't appear to take advantage of the 160 MHz bandwidth.  So with a 2x2 Antenna configuration at 80 MHz your internet bandwidth is likely at the maximum you can achieve due to hardware limitations.