2 Epson Printers not connecting TELSTRA SMART MODEM GEN 2 via wireless network

[BusyBod]

I have a Technicolor DJA0231 modem/router Version Champagne (18.1.c) only four months old, that has had two Epson printers (TX710W & XP-220) connected previously to router and worked fine to print to via wireless Network. Been connected to NBN FTTP for years. I suspect a firmware update of router has stopped this. Firmware Number 18.1.c.0543-950-RA

However, I now can't connect either Wireless Network even after factory reset on all printers, reset modem/router including complete factory reset, uninstalled and reinstalled new printer drivers. Tried turning off band steering and selecting the channel manually.

Even if I search for wireless networks on both printers, I can pick up other networks but not mine. Even, if I manually enter network will not connect.

[cf4]

A recent firmware updated enhanced wireless security by adding Protected Management Frames. You could try turning of PMF by logging into modem (http://193.168.0.1  password is Telstra) go to Advanced > WiFi  scroll down and look for Protected Mansgrment frames. Set to disabled and save settings.

If WiFi is still invisible then the 2.4 GHz WiFi is probably faulty. This is a common fault on these modems. To prove 3.4 GHz WiFi is faulty turn of band steering in the modem's 2.4 GHz WiFi settings,  this adds -5G to the 5GHz WiFi name. You should now see two WiFi names broadcast by modem on your devices that can connect. If you can't see the name without -5G then the modem's 2.4 GHx WiFi is faulty.

[BusyBod]

OK thank's for the information. 
After completing this I'm still unable to connenct to wifi. How do I go about getting a replacement modem.

[cf4 · Accepted solution]

Contact Telstra support using the messaging function in the get help section of the My Telstra app. Tell them the 2.4 GHz WiFi is faulty as non of your 2.4 GHz devices can see the WiFi. The printers only support 2.4 GHz WiFI. If codi sends you round in circles leave a message for a consultant from Telstra to contact you.

[BusyBod]

Codi is definately sending me around