iMac only connects to internet via Ethernet but other devices are on wifi

[2by2Gall]

Hi everyone, since I've changed from one ISP to another I am having problems connecting my imac to wifi. Its all setup and my phone and son's tablet are connected via wifi. Its telling me wifi is connected on my mac and I can send imessages, use viber and send/receive emails but to open webpages I have to plug the ethernet cable back in.
This whole time I can still use my phone on wifi.

I'm guessing it will have to do with some settings but can't work out what.
I have tried using Firefox, Chrome and Safari and non of them will open the home page let alone a webpage.

Can anyone help?

 

[learninmypc]

Just a guess, but in firefox go to Tools>Options>Advanced Tab & click the Network Tab & under it you'll see , Connection
Configure how firefox connects to the internet. To the right you'll see a settings button. click it & in the box that pops up, make sure NO PROXY is clicked & click ok to exit. hope this helps

 

[2by2Gall]

Just a guess, but in firefox go to Tools>Options>Advanced Tab & click the Network Tab & under it you'll see , Connection
Configure how firefox connects to the internet. To the right you'll see a settings button. click it & in the box that pops up, make sure NO PROXY is clicked & click ok to exit. hope this helps

I don't have the Options tab under Tools.

 

[2by2Gall]

These are the options I have