Hello and welcome to justanswer.com my name is XXXXX XXXXX X'm here to help you with your networking question.
What are the models of the router & range extender please?
Please try the easiest things first which is to power off both the router and range extender.
Then, plug in the router and wait for one minute. Then, plug in the range extender.
Can you get internet access now please?
Will the devices that can't connect, limited to say the router or range extender? If so, can you connect them if you move them close to the other device?
Never mind, I'll try another way to get an answer.
Hello there thank you for your reply
I'm not sure why you've rated me with bad service when I have asked you an opening question?
You haven't said exactly what you have tried.
You have only said:
Already Tried: I've checked the router and its OK.
This answer is very generic. Have you tried unplugging & replugging? I don't know what you are expecting first off as I need to understand your equipment configuration in order to help you.