2017 will connect to network but not internet

[imac275]

I have just come across a strange problem with my iMac.

When I come back to it after an hour or so of not using it, it is not connected to the internet, but it is definitely on my network as I can see all of the other devices on it.

All other devices connected to the network can access the internet fine.

Is that likely to be a software problem?

 

[imac275]

Did anyone have any thoughts on this. I temporarily fixed it by changing DNS as advised on another forum, but now back to square one!

It will connect to any network but can't 'see' the internet.

 

[chabig]

I’d look outside the computer. Start by resetting your router.

 

[Fishrrman]

OP:

Are you in a home environment, or a work environment?

If you're at home, I would power down EVERYTHING in the network.
Computer, router, internet modem (if you use one).
Then, power back up in order:
1. computer modem
2. router (if it's not integrated with the modem)
3. computer.

Does this help at all?