Usually, symbol errors caused by some physical condition and in many cases fixed by a) reseating BOTH ends of the cable or b) replacing the cable. If you are using OEM solution, you might contact the hardware vendor after trying reseating the cables and see if your equipment is under the warranty or open case with him.
In order to reset the fabric counters, use 'ibdiagnet -pc' command and the same command should be used to collect information about the fabric. ibqueryerrors, despite that it exists in Mellanox OFED, shouldn't be used as it not under the development. ibdiagnet is a swiss army knife.