Okay, the problem is these two things are related. If Joseph is enslaved soon after the war, and he's been enslaved for 500 years, that would put the end of the war 500 years prior to the RP. Sure, the internet, computers, and every part required for that to work could have been around that long (420 years to use your 80 year estimate), but logically the technology should be much much further by now. Like, this world should have teleportation, flying cars, and space travel. If it is still at a “modern” level at the time of the RP, then it couldnt have been around 420 years before, because then what was the advancement?

Furthermore, anything that exists can't be TOO far ahead or behind any other field of technology. For instance, if computing technology is that old, that's a big step towards robotics being more advanced. In which case why would they need slaves when they would have built robots by now?

You can't say, “Oh, it was developed then and then everything in the field just stopped” because the world and human progress doesn't work that way. Things slow down and speed up, but they don't just stop for hundreds of years unless a new technology that performs the same function comes along. Like, yes, we haven't advanced anything with vacuum tubes because they were functionally replaced by transistors which were superior in every way.

Am I making any sense?