I'm sorry for this basic question, but I'm stuck. I'm looking for some networking equipment that allows me to route WAN traffic (internet) to a client on a local LAN based on TCP/UDP port. That is, basically what you can do with a simple ISP router. The problem is, I have about 30 clients and can't figure out if a layer 3 switch (48 ports) can manage this NAT function or if I need a switch (layer 2) in combination with something else. I'd rather get something professional rather than a wireless ISP router which needs a reboot twice a month.
What the situation looks like more specifically is:
I have one network cable connected to the ISP. Then I have about 30 clients of different kinds (mostly HVAC automation devices) that speak different protocols, all over TCP/IP and on different TCP ports. What I need to do is expose these one way or another to the internet, so that I can access the clients externally. That is, using one IP address I want to connect to one of those 30 clients based on TCP port.
As soon as I'm able to understand the basic principles about this, and what kind of gear I need (switch, firewall, etc.) I will need to take another step to understand the security aspect in this. I obviously don't want anyone to be able to access my automation stuff.