Ecolink says UDP 5198 Receive Failed

> Attached devices; the laptop is an attached device. Just like the
> doorbell, Alexa, etc.

   Yes.

> The laptop has an IP address and MAC address.

   Yes, roughly speaking.  Strictly speaking, its network _interface_
has these addresses.  (If it has a wired interface and a wireless
interface, then each has its own, unique MAC address, and each could
have its own IP address, too.  But, in most cases, only one interface is
used at a time.)  For a computer with one network interface, it's safe
to associate the MAC and IP addresses with the system, but they're
really properties of the network interface.  When a system has multiple
network interfaces, you need to be more careful when describing these
things.

> Is the Echolink program running on the laptop a unique and separate
> attached device? Does the program need its own IP and MAC adresses?

   No.  A program communicates through a network interface, and that
interface is what has the addresses.

   When a message (like, say, a UDP packet addressed to port 5198 at
your external/public IP address) arrives at your router's WAN/Internet
interface, what should the router do with that message?  You might have
many different client computers/devices connected to the router.  Which
one should get this message?  A port-forwarding rule can provide the
answer to that question.

   For example, if you specify a rule like:

                        Service  External   Internal   Server
#   Service Name        Type     Ports      Ports      IP Address
1   Echolink on YYY     UDP      5198-5199  5198-5199  192.168.1.200

then the router would forward such a message to port 5198 at
"192.168.1.200".  If there's a program running on the system at
"192.168.1.200" which is listening at port 5198, then that program will
get that message.

   For an outgoing message, the router's NAT features handle the
details, remembering who sent the outgoing message, so that a reply to
that message can be steered to the source address of the original
message.  For an incoming message, no one knows the true destination
unless there's a port-forwarding rule (or some equivalent thing created
by UPnP).