@Cathy Moreau
I had this connection issue with my tab between zyxel vdsl modem.
I figured out how to connect wifi.
1st way
Just try to change pasword mode between somethings.(WPA2-PSK, wpa, etc.)
Then try connect your tab or phones to modem.
If it's doesn't work
The 2nd way little tricky
If you guys have the same possibilities in your modem's configurations..
You can give a shot my 2nd way too.
I created Guest account without password.
I changed some options for my Guest Account for some security.
1-) I hided my Guest Account's SSID. (invisible SSID) (just give a easy words or things to name on it about invisible SSID for you can remember always)
2-) I Changed MAC Authentication's MAC Restrict Mode option to Allow for my invisible Guest SSID. (just add 1 mac id adress. I mean, add your phone/tab wifi mac id adress to your list)
I added my tab's Mac IP adress to allowed Guess Account's mac filters.
Then i added my invisible SSID's name to in my tab wifi's netwoks option.
I connected my tab to modem easily