In the future, please state exactly what you tried that didn't work so as to not duplicate troubleshooting suggestions and in this case, which browser you are using to access the net. Thank you
Try this DNS server.
Open System Preferences > Network > Advanced > DNS
Click + and type:
Click + again and do the same.
Quit and relaunch your browser.
If that didn't help, open System Preferences > Network > Advanced > Proxies. Deselect any checked boxes on the left, quit and relaunch your browser to test.
If that didn't help, assuming you are using Safari, try troubleshooting Safari extensions and third party plugins.
Try troubleshooting extensions and third party plug-ins.
From your Safari menu bar click Safari > Preferences then select the Extensions tab. Turn that off if there are any installed. Quit and relaunch Safari to test. If that helped, turn extensions back on then uninstall one a time to test.
If it's not an extensions issue, try troubleshooting third party plug-ins.
Back to Safari > Preferences. This time select the Security tab. Deselect: Allow all other plug-ins. Quit and relaunch Safari to test.
If that made a difference, instructions for troubleshooting plugins here.
Network monitoring apps such as Little Snitch and others can prevent pages from loading as well as some manufactures of anti virus software.