I was going to recommend traffic manipulation and traffic shaping with netem and tc. I set this up at my last employer in the lab for use with our networked IP radios and such. Stimulating poor network conditions has been a mainstay in my testing ever since, even now that I work on web apps and distributed services.
Pretty handy for testing. I've used it to simulate a bad uplink in between a dslam and bras.
https://www.excentis.com/blog/use-linux-traffic-control-impa...