0.6 alpha 3 in AION looses speed (20-30%) after a half hour or hour of mining... and then, maybe after 2 hours, looses connection to pools...
I tried it on 4 different AMD RX 570 and R9 270/280 rigs and all acted in same way

Hmm ... thats odd - loosing connection may happen atm, as mentioned I am not happy with the stratum, but no idea why looses speed. Can you monitor clocks and heat and report if something strange happens in that moment? Here at mine the code was stable so far

No anomalies - I have no idea what causing that ...
so if you change the port number to 3333. from 9999. still loses connection to pool? to everyone who uses AION
Yes.