Smart TV not connecting to internet

[#1]

"You're connected to the wireless network but not to the internet."
This seems to be an overnight error, that turned up this morning ; (
Is this a Plus Net Router error? ie it's not allowing the TV to connect to the Internet? Or is this a TV error, that is somehow not being able to connect to the internet?
I presume its the former, but just need to work out how resolve it. I have downloaded the recent software update from the TV to no avail.
Could the DNS settings on the router have affected anything? Do they change overnight?! I have lots of crap I need to watch on Catch Up, so need it sorted!! ; )

[#2]

You might need to do a Smart Hub reset.
I had the same problem after a TV firmware update.
Have you tried leaving/re-joining the wireless network?

[#3]

I have reset the Smart Hub and have the following response:
Connected to your local network, but cannot connect to the Internet.
Check the DNS settings in IP settings or contact your ISP to access the internet.
What exactly do I need to check for in the DNS settings?? I have already switched the TV and router on and off and factory reset the router.
Thanks for the help ; )

[#4]

You could try manually assigning the IP address to the television :
IP = 192.168.1.50
Subnet = 255.255.255.0
Gateway = 192.168.1.254 (assuming this is the default IP of the router)
DNS = 8.8.8.8
2nd DNS = 208.67.222.222
If that works then just use it as it is

[#5]

Hmm this is strange - some other people have had the same problem http://community.plus.net/forum/index.php/topic,127596.0.html
It seems to be a Plusnet DNS issue.
Try DomS' suggestion and use Google's DNS.