Semi-Complicated Network

This guy has some good tips including HOW to turn off the wifi:

I have watched this guy before. He does make some good points. I had forgotten about the enable SSID switch. It makes sense if you do not have the SSID enabled then it should turn the radio off. Another source of information is on Redit as there are guys there that are having multiple conversations about the T-Mobile router. He is right taking the shell off to make external antenna connections is pretty easy. The MIMO 4x4 log periodic antenna can make a big difference in improving signal quality by reduction of noise and a stronger signal. You stated you had packet loss. Look at the signal strength RSRP and the signal to noise ratio SNR and try to improve the SNR as best you can. The waveform.com site has information about some external antennas but they are not cheap. The guys at waveform are very helpful and great about answering questions. I know I could improve my signal with the external antenna and have more flexibility to better locate my router in the house for WIFI signal spread but the ~$400 price tag for the antenna is more than I really wanted to shell out given other expenses from moving across country. 

https://www.waveform.com/a/b/guides/hotspots/t-mobile-5g-gateway

When placing the router it takes a little time to dial it into the best location. If there are multiple towers about there can be noise so using your house as a shield to get the signal you need and avoid excess unwanted noise. I found the window with direct north exposure to the tower was not the best one. I found a better signal with improved SNR in a NE window adjacent to the north facing one. If you can see the tower and know it is the one your signal comes from that is helpful. T-Mobile support should be able to provide tower coordinates if you ask. There are web sites you can look up where the T-Mobile towers are also. www.cellmapper.net is one site where you can get information on 4G LTE and 5G NR tower locations. It may not have the most accurate information on a given tower if it is not updated. A conversation with a T-Mobile support engineer should provide the actual location of the tower associated with the PCI signals your router receives. 

Do keep in mind that packet loss is hard to identify where that takes place especially when going out to an internet target. There are multiple hops and factors so it might not be a local issue. Compare wired vs. wireless when you are testing. Clients farther away from the WIFI signal source will have reduced speed. It takes considerable time to really dial things in. Have fun.

So, when you are stating packet loss I am assuming when running speed tests. If you are not familiar with networking tools such as Wireshark and reading packet captures trying to identify the character of the packet loss can be pretty daunting. I gave it some more thought and found a site that might help you zone in on it a bit more. https://www.dnsstuff.com/reduce-packet-loss When dealing with wireless networks and cellular connections that can be a difficult task. If the statistics on the local wireless channels look good and wired ethernet connections don't indicate a local issue then it is probably outside your control. Looking at the data on the cellular connections and understanding how that works takes a bit of time to ramp up on. Building a profile of the traffic during low volume times such as late at night vs. daytime or evening hours could help some. Getting the T-Mobile router in the best orientation to the source of the signal becomes a very important factor for good performance. I know my router is 5.3 miles from the tower and picks up 5G on the n71 channel so speed expectations are pretty well established for the conditions. If you link to a higher frequency 5G band then you might expect really good speeds. In a metro area there will be much more "noise" to deal with due to external factors. 

I think putting my Asus router in AP mode was a huge mistake. I cant access the admin any more.

I was able to get into my Asus router with the iPhone app and switch it back to "router" mode. I was able to get on the internet in AP mode, but the speeds were all over the place and I couldn't access the router via the web UI. I have my wife's PC connected directly to the ethernet port on the T-mobile gateway and we'll see how her VPN likes that when she tries to work tomorrow.

I just played COD on my PS5 and it seems normal. Not showing any data loss now on speed tests. I imagine our tower is pretty congested too due to the Super Bowl. Fingers crossed just disabling the WiFi on the gateway did the trick. I'm also hoping the wife's VPN works better plugged directly into the gateway. If not, that could be a deal breaker.

Ok we can't stream TV and play games at the same time. It's painful! My PS5 can't get above 6Mb upload. It's on Ethernet too. Apple TV streams via Ethernet as well. I dunno about this…