Is it possible to switch to the "router" mode somehow?

Are these features available out of the box?

OpenWrt is setup by default as a router.

What is your specific need? What is your hardware and OpenWrt version?

ubus call system board

Is there any way to make an L1/L2 router?

I don't understand what you want to achieve when you say you want to make an L1/L2 router. But the answer is no because that's not where routing happens.

A router operates at L3 -- this is routing and it operates with IP addresses when packets needs to traverse between two or more subnets. L2 is switching -- many consumer routers have built-in switches so they can have multiple ports for the lan. Switching is what happens when one machine wants to talk to another on the same local network. It uses MAC addresses. L1 is the phy (physical) layer -- this is the electrical signaling link (when talking about ethernet over copper).

Maybe it would be useful for you to review the OSI model (specifically the layer architecture section) to understand how data is moved/processed at each layer.

It's not clear, though, what you are hoping to achieve... can you provide us with a specific example?


is it possible to run openwrt in "switch" mode so as not to buy a "TP-Link LS1005 Switch"?

As a switch, sure. It's basically the same as a dumb AP, but without the wireless part. In general, just set the device such that it has an address on your existing lan (that doesn't conflict with any other static IP devices or the upstream DHCP server), turn off the DHCP server on the OpenWrt lan interface, and then plug the cable into one of the lan ports.

Nothing else needs to be done beyond what I just described (at least when considering a default configuration).