Wifi Modem changed/upgraded. Can not connect to Netgear AC750 wifi Range Extender

[colettem]

Telstra gave me a smart wifi modem with a different WIFI name. After the change over, I am unable to get the Netgear Extenstion to reconnect to the new Wifi. Any device still displays the previous Wifi name-ext. 

I referred to and used the instructions to make a change. Tried to connect to Netgear_ext WIFI on either of my tablet or mobile, BUT under the WIFIs to be selected,  the "Netgear_ext" did not appear for selection. I also attempted this processs the using the Nighthawk APP. 

I have also pushed the RESET button on the Netgear Device. I no longer have extended WIFI use. Can someone please assist me.

thank you

Colette

[plemans]

What extender do you have? AC750 is a speed. 

When you reset, did you push and hold reset for 7-15 seconds while it was powered on? many just click the reset button. 

What router are you connecting it to (model)?

[colettem]

What extender do you have? EX3110 NETGEAR

When you reset, did you push and hold reset for 7-15 seconds while it was powered on? 

I will try to do this again.

What router are you connecting it to (model)? TELSTRA SMART MODEM, 

Technical stuff

• Inbuilt, pre-activated SIM to connect to 4G when required
• DSL port for your ADSL2+ or VDSL2 home broadband connection
• 4x4 802.11ac – the fastest ratified Wi-Fi standard
• one 3.0 USB port
• one gigabit Ethernet WAN port
• four gigabit Ethernet ports
• WPS push button
• Dual band capability (2.4GHz and 5GHz)
• 256MB RAM

it was previously was a Telstra Wifi modem that relied  on the NBN working.