Hi,
just got a GL-AR750S and am trying to understand what I’m seeing with ifconfig and how it relates to how the device physically looks like.
Physically the device has:
- wifi 2.4G
- wifi 5G
- WAN ethernet port (1st in direction left->right)
- LAN ethernet port (2nd in direction left->right)
- LAN ethernet port (3rd in direction left->right)
A compressed view of ifconfig -a and brctl show (some interfaces were skipped) :
br-lan
* bringing eth0.1, wlan0 and wlan1. Conceptually that is a switch with 3 ports.
* the bridge itself [has an IP address](https://unix.stackexchange.com/questions/319979/why-assign-mac-and-ip-addresses-on-bridge-interface) (192.168.8.1) serving as the web UI
eth0
* A normal Ethernet interface
* Not clear how does it relate to the two physical Ethernet ports and what can one do with it?
eth0.1
* A VLAN interface
* Not clear how does it relate to the two physical Ethernet ports?
eth0.2
* Another VLAN interface
* This seems to be tied physically to the WAN port. It has an external IP when it's connected to a gateway
* Due to being in a separated VLAN this is only accessible via routing
wlan0, wlan1
* guessing these represent access points for the 2.4G and 5G wifi's
teql0
* don't know what this is
This is as far as I got.
If someone can fill up the unknowns or correct what’s wrong, please feel free to 
eth0 is the CPU port, while eth0.1 and eth0.2 is the vlan interface which based on eth0.
eth0.2 bind with port 2(wan), and eth0.1 bind with port 0 and port 1(two lan).
Please refer to [OpenWrt Wiki] Switch documentation for more details.
teql0 is a virtual network interfaces, which facilitates a queuing approach via the tc (traffic control) tool.