Multiple Arduinos with Ethernet

Projects General Guidance
1

I have a project that has used a Nano with Wiznet Ethernet. It works great for years.

I've just added another arduino with ethernet, and now everything's hanging unpredictably. They just can't seem to along. Even hanging other ethernet devices I talk to.

I've assigned the second Nano a unique IP address on the same subnet aseverything else. Do I also have to assign unique port number and/or Mac Address?

Feeling like a dum ass!

2

Port number need not be unique, but the MAC address must be unique!

3

I've assigned the second Nano a unique IP address on the same subnet as everything else. Do I also have to assign unique port number and/or Mac Address?

Well, with out the code you are using and just what type of communication you are trying to establish, not much can be be deduced for the issues you are having.