Fibaro and smartthings

I have V3 hub for several months and about 30 fibaro 2 double switch ZW5, 10 fibaro shutters 3 ZW5, and 3 BTK smart plugs , all ZW5.
I am having repeating errors and unavailabilities of the devices, no one specific device but random and sporadic devices involved.
doing Z wave repair- there are also many errors, even after I’ve excluded all devices and reincluded them gradually with repeated Z wave repairs. at first it looked promising but afterward it came back to square one- many errors and unreliability.
So far smartthings support couldn’t help much.
Is it fibaro problem or Z wave general problem or is it smartthings unreliability or only my bad luck?
Do you have any suggestions?