I've tried different firmwares and the best i've found is version 20180930
Stable hashrate, no need to reset the miner and overclockings works also good.
CAN ANYONE HELP?
That is interesting. I had the opposite experience. I rolled everything back to the original firmware and although the interface mining numbers are garbage, my actual pool hash rate, with overclock, is over 7.2 gh/s with my original Zig Z1. (prohashing) When I put the 09/30 or 10/15 firmware, it would crash and have horrible hashrates with the overclock.
Either way, I am trying to sell it, but that is because I have super strict requirements through my work as it pertains to mining cryptocurrency (since I work in securities law) so it is a massive extra headache to have to preclear all my mining ever 3 days