So it worked 20 days ago, and nothing has been changed?
The wall outlet (same size as for a phone (4 wires)) should be connected to the DSL jack on the modem. There may be a filter (small white / tan dongle) at the wall jack. See image below. An Ethernet cable (8 pins) would connect between a Fibre Optic ONT, and the WAN port.
If the troubleshooting tips (especially if the Internet light is lit or not) didn't resolve your issue, you should contact Telus to do further assessment from their side of things.
That's not a wifi login. That is a device registration login. Did you get a new router or something? How is your home network set up and which devices are you using? (modem, fiber box, router, switch?) Also if you reboot your modem, does the problem go away?
What is the WAN port wire connected to? Does it connect to something else on your home network? If yes, that could trigger the problem you are experiencing. Do you have a fiber optic connection?
Can you take a few minutes, and step through these questions?
What is connected to your modem, and to which port?
Do any devices work on your network?
Is your bill current, and fully paid?
Have you tried these troubleshooting tips?
In addition: has anyone in your house connected anything to the cable in the WAN port that you know of? If someone has been using it for more than one device that could use up all the available IPs you have. If that's the case Telus should be able to clear out the extra devices in the registration page that's popping up.
Disconnect the WAN cable.
Does the phone connected to the Phone adapter work to make & receive calls?
Have you a laptop or computer you can connect to another LAN port?
How is your modem connected to Telus Network? To a telephone-type wall outlet, or to a Fibre Optic ONT device (usually white in colour)
How long has this problem existed?