Hiya, so you can find the WiFi network on mobile devices but not your computer? What sort of modem do you have? If your modem is the AC modem, your computer may not be compatible with the 5ghz signal, so the WiFi name could be different to what your mobile device is connecting to. If you need a hand with troubleshooting, please chat with our Tech Support team
Yes if you have the AC Dual Band Sagemcom Router it is best to have 2 SSID's add 5Ghz to your 5 Ghz Band that way you always know what you are connected to and can can change at will.
Works perfect for me has done so for years.
What I should have mentioned above is to keep the password the same for both 2.4 Ghz and 5Ghz only change, add to SSID.
You don't want to have to change your password every time you change from 2.4 to 5 or back.