How to determine in C# if there is a client with a given IP address on the local network?

Question

Computer networks

There is a p2p application that receives a list of port forwarding from a NAT device using the IGD protocol. How to check if there is a client with a specific address on this local network?
Don’t ping him, after all?)
(I foresee a situation when the client’s wi-fi suddenly drops, and when the connection is reversed, dhcp gives a different ip-address. In this case, the forwarding will remain active for a long time, the router itself does not throw off dead forwardings)