If you don't want to use ethernet cabling and want hundreds of Mbps speed wirelessly in your home, you have to improve your WiFi netwerk situation. That could mean buying extra (very) advanced WiFi accesspoint(s) and maybe even a new smartphone in order to reach 750 Mbps. Or maybe ask all your neighbours not to use WiFi and not to use their microwave oven, so that the wireless capacity in the air is all there for you exclusively. Or go back to KPN. But I doubt that you got 500Mbps via WiFi there. So the call scenter is right.



On the other hand, what application needs 750Mbps from/to the internet ( and full duplex, so simultaniously 750 DL en UL) that you use?

There is none I would say.

It is more like that T-Mobile wants to offer 'more-is-better' ( 750 is better than 500, right?).

If you want 750Mbps in your home, you don't need '750mb internet'; You actually don't need internet at all in theory, you just need the right cabling and/or equipment, not the help or services of an internet provider.

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Indeed. Wifi is not as stable as cabled internet. You may be able to upgrade wifi, but that's not possible with the router/modem T-Mobile supports. An alternate router is recommended, but even with a new router it is highly unlikely you will have a 750/750 connection by wifi.



Your router/accesspoint/etc need to have the latest standards on 5Ghz as well as a strong antenna. Your gear needs to support this standard as well.



Besides you need to analyse available channels and chose a free channel as interefence from neighbour networks can impact the speed drastically.



If you do not want to use cable, because of the large amount of dedicated devices, you could use powerline adapter, but honestly I do not know the specs on supported speed.

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