In some cases, it could be that You'll need to know your ISP since the Supporting Agent asks for it or in case you are using an ISP device.
You can check your ISP under this Link:
What is my ISP?
I know my ISP now. What do I do?
In the first case, the Agent asked for it, so you can simply forward the information to the Agent.
For the second case, please get in touch with said ISP since the device you need support for has been provided by them, and we cannot support it henceforth.