Hardware errors are very normal to have, it's a waste of time to try and determine what number of errors is good and whatnot, the most important would be your accepted hashrate on the pool, it accounts for all hardware errors, stale and rejected shares if your daily accepted average is very close to the hash rate that shows on your miner status page, then probably everything is fine, if it's off, then you need to troubleshoot.
Generally speaking, hardware errors is directly related to the hash board frequency, the higher the frequency the more errors you get, if you think for example the middle hash board is getting too many HW, then you will need to lower the frequency for that board, not sure if the firmware you use allows that, if it doesn't, there is nothing you can do about it.
Also, please do yourself a favor and stop mining to Antpool.
You probably mean 1.6/1.7 ph or 1600/1700 th.