after updating to 4.4.2 from 4.3 on my T-Mobile note 3 i lost unlimited wifi tether after trying many things i came to an app on the play store called "wifi tether router" it needs root but if you already have root and are looking for a solution witch many are this app works flawless. all instructions needed are on the web site but simply you go to your settings-more network-mobile networks-acsess point names hit the plus to ad a apn. give it a name any name will do. after that click on "apn" and give it the value "fast.t-mobile.com" minus the quotes. after that check that the protocol is ipv4 and roaming protocol is ipv4 it should be set already but just make sure. save your new apn. select your new apn. reboot phone
go to the play store and look for an app called wifi tether router it costs $2.50 but worth it. install and setup your ssid and security and password. then just check to make sure your apn you created is still selected go back to the wifi tether router and select enable it will take about 10-15 seconds to fire up and your all set. i have not needed the user agent switcher on my computers but you may need to and more so if you have no tether alotment in your data plan.
its worth a try if nothing else and i have never had a problem getting my money back so if it dont work for you get your money back. if you have a T-Mobile note 3 rooted and use this method you should be enjoying tethering. this app needs root and i would think a lot of other rooted phones would work with it also. its been worth it for me anyway i think you could enjoy it also
pm for questions if need be im always happy to help