Rax50 Inconsistent speeds across different devices

[cscott1]

Hello community I was hoping to get some clarification on some surprising numbers I'm getting on speed tests with my new router. My setup is the following I have Xfinity gigabit service 1200 download 35 upload. Using a Netgear cm1000v2 modem and a Rax50 with the most up to date firmware. When doing the tests via Ethernet on my Nivida Shield TV the Ookla speed test shows the full download speeds that the cm1000v2 is capable of. Clocking in around 950 download 42 upload. Netflix's network check shows a connection speed of 527. Definitely nothing to complain about with those numbers.
However when I do the same tests via wifi on the 5Ghz channel the numbers are significantly lower 200 download and 42 upload. I was getting 320 down and 42 up with an older Netgear R6400v2 ac1750... Insert facepalm.
Now when I do the same tests on my Google pixel 3 on the 5Ghz channel I get better numbers 600 download 42 up and the nighthawk app gives me the same numbers as if I were hardwired 950 down and 42 up. So what is the real numbers? I understand you will not get full speeds over wifi and the hardware of the device you using plays a factor in the tests. I guess I'm just confused by how the tests can be so different and what blows my mind is how is a 5 year old routers wifi is out preforming the Rax50 to my most used device. How can this happen?
I got the Rax50 lightly used on OfferUp for 80 bucks so I feel it was a good purchase however if I had payed the new price of 250 at best buy or the like I wouldn't be so sure.
Starting to ramble sorry anyway the router is using all the stock settings anything I can try to improve the download speed to the wifi or is that number really irrelevant when it comes to streaming? I do occasionally download files movies and whatnot and upload YouTube videos. I know those numbers are important for that.
I have 4 Android tvs a, couple phones a couple laptops and a Rumba connected to my network but seldom are they used at the same time. Maybe one 1080 stream on one of the TV's and maybe 2 phones being used simultaneously. We don't really have any smart home products at the moment aside from the Rumba but looking into the possibility of expanding in that regard particularly with some security cameras.
So should I start messing with the setting's in the routers web based user interface the genie or whatever it's called or leave well enough alone do I need to run Ethernet to my Nvidia shield of is 200 Mbps already more than enough? I have a short period to return the router if I'm not happy with it so what are some other things I'm not taking into consideration that I should be? Sorry for such a long winded post and I appreciate any comments or suggestions.

[plemans]

200mbps is more than enough for gaming/streaming. Even 4k only needs 25-40mbps for streaming. 

so hitting 200mbps, you won't have issues. 

to explain the speedtest issues can take a little bit. 

First off, when you speedtest using the nighthawk app, it actually hosts the test directly off the router. So it doesn't involve the wireless variables. This can be the best speed but it can also be slower. Reason why is the built in speedtest in the nighthawk app doesn't always pick the best test server to use. So sometimes it'll max out gigabit, other times it struggles to hit 300mbps. I rarely recommend it when someone has speeds great than 500mbps. 

When you're hosting off wifi, then it involves a lot of other factors such as interference, antenna's in the device testing off, DFS channels, etc. As well as it can involve the same issue of did speedtest choose the best server to test off or not. Its why the actual speedtest app lets you choose different servers. Many factors influence this. 

the most reliable indicator is testing hardwired into the router and testing off your ISP's speedtest site. Tends to actually max out a connection and the hardwired means there isn't anything interfering with it.

From the sound of it, some of your devices are doing great on wifi with a couple being a little slower. "little slower" still hitting 200mbps. Unless its causing issues, I wouldn't worry about it to much as 200mbps is more than enough for anything but massive data transfers