the Message buf should be larger than 65536

[ColdwindY]

the Message buf should be larger than 65536,otherwise if -s 2000 then System.ArgumentException.
The max ICMP pkg is 65536. So just set
public byte[] Message = new byte[80000];
at line 39,ICMP.cs

[Killeroo]

Thanks for pointing this out. Yeah this seems to be a bug with the way that we are updating the ICMP message field, will submit a fix soon.

[Killeroo]

This should be fixed in the lasted release, you can download it here.

[Killeroo]

RecieveBuffer is now set to max ICMP size, closing this for now 👍