In a classic server-client situation, your clients should have AllowedIPs set to 0.0.0.0/0, ::/0 in their repecive configuration file.

Only if you want the VPN to be your default route! Many may not want this.

Good lawd, these are the basic tenants of networking. I'm so sad people are unfamiliar. Let me throw a few more tricks your way:

• telnet or netcat (nc on CLI): check if a port is listening and available
• wget or curl: find out if an HTTP server is listening (or whatever, really)
• netstat: kind of phased out on modern *nix distros, but useful for checking connections from hosts (you can still install it, but has been superceded by...)
• 'ss' : same deal, different name
• 'ip route': check your routing tables to make sure traffic goes where you think it should

Check the docs, or search around for your particular usage, but these are all the barebones tools you need to figure out networking issues quickly.

The "allowed host" on the client side is to put the networks in you would like to route to. If you want to use the VPN tunnel for your default route it's when you use the 0.0.0.0/0

Wireguard will definitely not work first try.

And... why not? OpenVPN is 10 times worse because of the mess they've made with push route and other options.

your clients should have AllowedIPs set to 0.0.0.0/0, ::/0 in their repecive configuration file. I found this pretty counterintuitive, b

Why would you? Those are the IPs that the client is able to access through the VPN tunnel and 0.0.0.0/0, ::/0 means all IP addresses, totally NOT counterintuitive.

You need to tell sysctl to forward IP traffic,

Yes, maybe... but not permanently at least. You can setup it on the server conf file via PostUp and PostDown:

[Interface]
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

If required prepend sysctl -w net.ipv4.ip_forward=1; sysctl -w net.ipv6.conf.all.forwarding=1; to PostUp and remove with =0 on PostDown.

The downside of you described is that you're enabling IP Forwarding permanently and even if the WG tunnel is down. This may pose a few security concern in some situations.

Another tip: On Android phones, Tasker can be used to automatically activate Wireguard tunnels to your own or a commercial VPN host. Taskernet.com has one project that activates WG when off specific wifi networks, and another that I wrote that allows you to activate a tunnel on demand only when you open specific apps. Great if you want to access a home server occasionally (without detectable open router ports) or want an extra layer of security when running a financial app.

"AllowedHosts" is the one thing that pisses me off the most. It's a terrible name and caused me tons of confusion when first setting up wg.

I set up my server too, and other than the fields in the configuration and some iptables rules (I really should switch to nftables), it wasn't a big hassle. Worked perfectly. But yes good tips about IP forwarding, I did it in the file directly but that can be a problem

I mean...all this and much more is part of the wireguard archwiki. And whoever wants to setup a wireguard server but doesn't know what ping is... Interesting would be an example on how to use tcpdump and how to read it.

Wireguard self hosting

I parsed this as Wireguard self-loathing and thought "that's a little harsh". :-)

Wireguard works out of the box for me. I use a docker image.

Another tip: take a look at systemd-networkd for managing your network connections! It has builtin support for creating wireguard tunnels and it's very nice.