So I just ordered the cheapest AP I could find.
Except the damn device worked perfectly. Slow but rock solid.
One of our testers at $CURRENT_JOB also has trouble simulating a crap network, because our network is good.
For testing we ended up building a small linux box to proxy for the test environment in the office. We could throttle the throughput to any arbitrary level, introduce latency, and introduce packet drops. It's amazing how poorly a frontend will work when you throttle the network to 128kbps, and introduce a small percentage of dropped packets. But once you get the system to work (for some definition of "work") under those conditions you feel pretty good about deploying it.
If you're testing hardware or vm's that don't support it or don't have root, you can stick your linux box transparently in the middle by bridging two interfaces, and apply your traffic mangling there. Testing wifi? Use a decent WiFi AP connected to one of these bridges and mangle your traffic once it hits the wire/after it stops being RF.
At a previous job I had a linux box set up with multiple bridges (each set with a different "testing profile" on different vlans) and trunked to a physical switch. Made it very easy for people in the office to attach physical devices through known bad network links by either using pairs of physical switchports or just dumping VMs/SSIDs into the right VLAN so they could test different things (simultaneously) without needing to reconfigure the actual mangling.
Worth noting that tc applies to egress traffic, so if you want a uniformly bad line it needs applying to both sides - but it does mean you can simulate unidirectional link problems too.
https://highscalability.com/how-facebook-makes-mobile-work-a...
Unless it's for a custom physical device, then uh. idk. Probably something, proxying through another computer that is hosting a separate wifi network? But likely a lot harder.
Oh? How does that help for native applications?
> You can always also simulate bad WiFi by walking away from your access point until you have bad wifi
That's unfortunately very inconvenient when you work on an embeddeded device prototype that consists of several boards interconnected by hair thin wires :)
Maybe I should make some friends across the street to the point they give me access to their APs...
If you're going for realism, bad wifi is a radio signal problem.