Hi Julie-Anne and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially yes; the Epson Expression Home XP-235 needs to be wirelessy connected to a Wi-Fi LAN or more specifically to an access point or commonly called the wireless router.
The iPad would also have to be connected to this access point which would thus serve as a common link to all the wireless devices in your home.
That way the iPad can send print jobs to the XP-234 wireless (through the router).
To my understanding, yes as the N300 series has WiFi capability.
Do the same procedure when the iPad was configured to work with "...Telstra air free hotspot wifi..." (note down the settings so it can be re-configured back).
To connect the iPad to the N300:
The SSID and password/Security Key is normally printed on the Wireless Security Card that cam with the N300 when new.
Can you try doing a RESET of the router?
Try using the information from the card. If still a no-go, perform a RESET and then try again the SSID and Security Key.
Of course; when able.
Let's try the RESET tomorrow or when conveniently able.
Hopefully the N300 is not LOCKED with former Internet provider.