Router and everything is definetly not the problem.
IP adresses work 100% and other miners than S5 have no issues at all.
Nicehash might be an option, i will switch 10 to another pool and see if it changes.
Any idea why nicehash crashes them?
Nope but when I moved mine to f2pool they were up for weeks instead of rebooting them daily.
Quite a few people have experienced this, all turned out to be nicehash related.
I have been on Nicehash for 24 hours and have had to reboot twice. I think the low difficulty of mining shitcoins sends an AntMiner into a circle jerk on the Interwebs. Am I right here?

Most likely, yes. Nicehash of all pools seems to quite aggressively throw out low difficulty shares which will lock up some hardware, including the S5 usually.