Wifi Router Zyxel T-54 can only connect iphone using QR code but not manual password

Hello Community,

So I contacted T-Mobile and they recommended that I make a post here.

Basically, on my modem Zyxel T-54 I cannot connect any device using the password input.

When I try to connect my phone for example, and use the password characters input, I cannot connect… then if I use camera and scan the QR from back of modem, it connects.

Then, I got several products which use Wifi, and all these are not able to connect to the wifi router.

Already changed the Wifi to 2.4 and 5g separately, also disconnected 5g just to guarantee devices support only 2.4g will connect, but nothing works.

I keep getting the messages on the devices I try to connect saying:

“Failed to connect to Router”

“Check if wifi is fine”

“Check Network and retry”

Also, very strange thing, if I change the name of the Router wifi, and/or the password instead of the Default as shown in the back sticker, the wifi cannot be connected and it says for instance on my phone “unable to connect to wifi” or “ wrong password” even when I copy the password from a picture I took of router (cannot make spelling mistake).

Basically, Tried all the standard things.. Reset modem, changed configuration in router to separate 2.4g to 5g.. give them different names to guarantee devices are connecting to correct wifi settings, and nothing solved it.

Even my phone could no longer connect when I changed the name of wifi.

And same thing when I only changed the password of wifi.

Nothing is working… 

And before I had all the devices connected using Ziggo, and with a different modem.

Could it be the modem that is faulty?

I asked T-mobile to replace the modem and also a different model to troubleshoot from there.

It seems it is the case, but at first the colleague of T-mobile was not sure if they would allow such troubleshooting… Very not nice!

Any ideas from the community?

What to try?