Having trouble turning off my WI Fi Gateway on my 5G home Internet BEWARE

Been fighting with this home internet 5g for 7 hours trying to use a Cat Cable to connect to my PC that I was on to put in the IP address that T Mobile uses on a private address, and, although there are several videos online that state that you can go in the T Mobile website and turn off the 2.4 and 5G to just use the T Mobile as a Modem, and after researching for a week before i purchased this due to me having a TUF- 5400 Gaming router made by asuz and also a RT-AC88U and these routers are 6G compatible, and I have talked to 4 different T Mobile techs, and the last one was helpful but the cat cable for me to get my Asuz 5400 back online due to the issues of T Mobile stopping me from turning off the Wi Fi so it doesn't conflict with my signal, and if streaming I won’t incur bottlenecking, by using several devices at the same time, and the unit runs cooler I was told, by a U tube video, well it turned out that out of 2 techs they had no idea how to do this, and I was told that my security was in jeopardy if I did this, and what I explained to them is Asuz has a integrated security system in their Router Software when you purchase it, and so what they were saying was bogus and wasn’t true, for I researched this for over a week before ordering the unit, from T Mobile….and even asked questions first to make sure that I could do this with no issues, and I found out that the only way was to connect a cat cable from the 5G unit and my computer and it still would not pull up the site to manually put in the information to turn off the WI- Fi to use this as a modem only instead of a router combo, and to have a better connection through out my network, and A Mesh system in my home. It is a shame that the techs do not have any idea how to go in and let you turn off the Wi-Fi and the although I was told when I bought the unit I could, and the videos that were on U Tube they brought up the T Mobile site on their PC’s and adjusted the Wi Fi to be able to do this and I was told by 2 of the techs that had no idea what I was talking about, and one kept on about the cell spot hardware from T Mobile that was replaced due to wear and tear for I had it since 2016  that they gave me over a year ago, and I had to explain to him 5 different times the same thing, about connecting my router instead of using the T Mobile 5G instead,  and he still had no idea what I was talking about, and he got frustrated and got off the phone so I had to call T Mobile  back again to get someone with enough sense to understand English comprehension, I have done everything that they wanted and, the T Mobile 5G still to no avail will not even let me go to the IP address that is public so I can use the service to manually change the settings like i was told by a supervisor at T Mobile the Cat Cable to the unit and to the PC to adjust the settings on public did not even work I got was a 404 page and issues with not getting to what he suggested I do, I reset my Asus router and I caught hell trying to use the T Mobile unit to get it to even work so I had to go back to my old provider and use it to try to get everything online due to the techs not knowing what they were even doing, because they do not listen when you try to explain this in a manner of understanding, because I have had to repeat mysel so much with these techs that I thought I was a broken record, they have an attention span problem, I do not even see how they got a job in the first place, and I was told that a simple tech change like this I am told that they are not trained for this…..So, I had to talk to an much older gentleman that is tech savvy and still no results due to the Gateway not wanting to let you login to your router or you asuz router…. And then I was told by a tech that my routers were not compatible, and i told him he didn’t know that he was wrong as long as it is a 6G compatible it will work with 5G and he stated he didn’t know this, why? When you are supposed to be a tech? Just goes to show that these techs if they aren’t 3 level techs they are in La La Land…..i knew more about it than their techs did and I am a customer, so I say beware, for I cannot understand why these techs are so untrained in just turning off the Wi Fi so the customer can enjoy his set up according to what he has or she has in their home as far as their personal network, T Mobile needs to change this wit a quickness because it looks like i will have to look for another provider soon, all because of telling me they could do this when I bought this unit and now I have it and I am told i cannot, is not right and they need to rectify this kind of misleading people like this”…..