I have an unused Raspberry Pi 4 (2GB model) lying around and I would like to install OpenWRT on it and use it as a router. I get Internet from DSL so I can't hook it up on the Raspberry Pi directly, I need to plug an Ethernet cable coming from my actual router to the Pi.
I am no expert on networking, so please forgive me if I say something that is wrong. I want the WAN coming in from the router from the Pi's Ethernet port, and the LAN coming out as Wi-Fi. I may also stick an additional Ethernet adapter to it in the future. I have tried doing this many times and have failed. So, could anyone explain to me how could I do this?
Also, what are VLANs, what are their uses and if I wanted one, how could I setup it in OpenWRT?
I honestly think you would be more happy with any hackable (openwrt compatible) router over the pi. The pi is great for many things but for a router is really lacking.
To add a bit: With VLANs you can have several 'virtual' cables inside of a real (physical) cable. You probably don't need it in a home setup, I'm not sure. It's for use cases like you just have one ethernet port or one cable running through the wall, but you need two (or more) entirely separate networks on the other side. Like the telephone network or the seperate server network along with the normal network, all over one cable. It works by tagging all the network packets. In the end it's just a number that gets attached to the packets and the other side knows how to handle the packets with those additional numbers attached to them. And it can send them out through different ports again.
At home, most people just have one network, so that kind of functionality isn't needed. Some people put their TV set, NAS or the smart home devices or their home office and/or guests in different networks so the devices can't mess with each other. A VLAN might be handy for those kind of things. And OpenWRT has VLANs, too, since there are two separate networks attached (as with every router). In this case the WAN side, going to your ISP, and your LAN. If you have a router with like 5 ports on the back, you can map those to either port if you change the VLAN settings. The labeling (WAN/LAN) from the manufacturer is just the default with OpenWRT.
I don’t think I am special but I have a few vlans setup. May main concern is using cheap “smart” devices from china and isolating anything they see or do to their own private network.
I also have a vlan setup for my guest network because I let my neighbors use it and wouldn’t want them exploring my nas.
While trying to set up the WLAN, I couldn't connect to the AP, it said no internet access, and I couldn't connect to the Pi, or ping any device from it.
Can't you find something like a guide or walktrough? I can't believe you're the first person using a RasPi as an access point...
I mean I would love to help. But it's a bit difficult without seeing the situation. And "I can't connect to anything" isn't exactly detailed enough to lead me to any conclusions. There are a lot of moving parts in a router, the wifi itself, DHCP, routing, firewall, ...
If you want to use the PI as a router you'll probably end up with a double NAT situation which isn't ideal but may work well enough. In terms of wifi performance, I wouldn't expect a Pi to be particularly good here so I'm not sure this even worth it unless it's just a budget issue and you don't have any other options.
In terms of your problem, you should be able to assign the Pi ethernet port to the default WAN and WAN6 networks. As for wifi, the Pi adapter needs to have support for AP mode, and looking around it doesn't seem clear if the built in wifi adapter supports that or not (most people using the Pi are using it purely as a router and not a wireless AP). If not, you'd need a USB wifi adapter that supports AP mode. You might want to get that additional ethernet adapter too for testing/debugging and it will allow you to add a dedicated wireless AP.
This a can versus should. You can do this but I would strongly discourage it. I would strongly recommend buying a proper device with Mimo and multiple reasonably sized antennas.
OpenWRT should have VLAN support out of the gate. Probably has an admin page for it.
Unless you want to go full wireless I would strongly suggest at least one USB ethernet dongle and a cheap managed switch (managed so you can take advangate of VLANs. Unmanaged switches are cheaper if you decide VLANs aren't for you).
I agree about the USB Ethernet dongle. Unless you only require short distance wifi range (eg hotel room temp router) the radio in the pi isn't going to be enough
I built a pi4 router a few years ago, and it's still running great, I recommend the project. But unfortunately I can't find the HOWTO and it was before I started taking good notes. I assume your current router is a phone company supplied modem/router?
My setup is cable modem-->pi router-->switch--> old netgear router in Access point only mode
Being that your router/modem is upstream of router, I'm not sure if you could pass-through the WAN to the pi router, and pass back the LAN to the router/modem for the wifi... maybe someone on here can shed some light?