The exclamation point proves that your network is restricted. This should be because your router settings are not completely correct. Please reset it. It's best to set it up with a wizard. ? As for your computer, it can connect to the Internet. The phone and tablet can't be connected. Maybe you didn't open the line. Routers can set restrictions on the connection of several devices, just like me. Just set the number of channels. If you don't want others to discover your wireless network, please turn off the broadcast.