I have the same problem and so far Canon cannot be bothered to come up with a viable solution. We either change our T-Mobile provider or buy a different brand printer.
Me too! MG5420 I was told by one tech person that the only way around it is to get a router attached to the modem and connect the printer through the router. Haven't tried that yet.
After spending the better part of two days with T-Mobile technical support I was finally told the best thing to do is buy a router from Amazon for $38 and connect my printer (MG5420) through it using WPS. I'm not sure who is the most at fault, but I ...