AC1750 smart WiFi router is no longer letting me connect to 5G

[Jcbuckley]

I have an IPhone 6s and iPad. When I got my new service, the new router and a new extender I could stay connected to the 5G anywhere even outside. Had problems zooming lately and noticed phone wasn’t  connecting. I powered down the router and reset network settings on my phone and says password is incorrect. My iPad was connecting until I reset things on that too. I see the 5G on the devices but won’t let me connect. Any ideas? 

[plemans]

1. what router do you have? Ac1750 is a speed

2. What firmware is on it? 

3. you said you have an extender as well? which one and firmware? 

4. What modem/gateway do you have?