I look to see what is using my network and there is strange mobiles, how can I block them, I thought it was password protected as I have to put a password in if I add a computer or laptop through optus yes
Sometimes they can hack the password by fast trial and error. Other times a Bluetooth device can let them in the back door, where they see your password on the network. The devices may be things that you let on, like your tv and toaster. How many nanny cams, security cams, Bluetooth teddy bears do you have?
Change your password and ssid. Make it a long password. Aaaabbbbccccddddeeee0000. If they get back on, then its a Bluetooth problem.
Some routers allow you to block MAC addresses.
Hi rocky50, best advice is to make sure you've updated the password and also edit the default WiFi username by logging into your modem see - http://www.optus.com.au/shop/support/answer/modem-or-wifi-username-password-help-fixed-broadband?req... for instructions.