We will use a Raspberry Pi and a managed Switch in order to extend the Pi's Ethernet Port to a LAN and WAN Port using VLANs with OpenWrt. This will effectively turn the Pi into a Router with a WAN port and multiple LAN ports. I will be using a Netgear GS308E Switch (ASIN: B07PDHVZNS), but you could use the following switches as well:

Zyxel GS1200 (recommended): ASIN B0798PKGFQ (8 Port) or B08K2KKK86 (5 Port)
Netgear GS305E: ASIN B07PHNTV45
TP-Link TL-SG108E: ASIN B00JKB63D8, 5 Ports (TL-SG105E): ASIN B00A128S24

0:00 How to add Ethernet to the Pi
1:20 Installing OpenWrt
3:31 Log into OpenWrt/LuCI
4:04 Choosing the Switch
5:05 Configuring the Switch
8:46 Configuring the Pi
10:27 Connection Test
11:02 Configuration Recap
12:07 About Security
13:40 About Performance
15:01 Adding a USB Ethernet Adapter
16:21 Some Finetuning
19:31 About Wi-Fi on the Pi
20:22 Final remarks

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