I have M4250 unable to to connect to the internet by OOB. I wanted to use as audio video connection

The M4250 is a switch. Nothing to do with Mobile Routers, Hotspots & Modems.

 

While many questions about routers are generic and could be answered anywhere, some things need specialist knowledge.

You might get more help, and find earlier questions and answers specific to your device, in the appropriate section for your hardware. That's probably here:

Discuss Ethernet Switches Plus and Pro Managed

I will ask the Netgear moderator to move your message.

In the meantime you could visit the support pages:

Support | NETGEAR

Feed in your model number and check the documentation for your hardware. Look at the label on the device for the model number.

Check for various troubleshooting tips.

You may have done this already. I can't tell from your message.

I mention it because Netgear stopped supplying printed manuals and CD versions some years ago and people sometimes miss the downloads.