hi
we have a building which has 500 devices in one lan
but want the above router to route just 50-70 will the hap3 manage it good ?
what are the parameter to look for
any pointer would be appreciated

Try to spend some time to explain better what you want...

500 devices in one subnet ?
Can't be done.

Serious, you need to be more clear on your requirements, yes.

500 devices in one subnet ?
Can't be done.

Why? Do you think that 192.168.0.0/23 is too bad for this? Or 192.168.0.0/22?
The efficency of this router could not be good enough but IT COULD be done.
And yes, more details please.

Yes we use MikroTik routers in networks with ~800 active devices without problem.
If a certain router can handle it is usually more dependent on the amount of actual traffic than on the number of devices.
(of course there also are limits on that, but they are not so likely to be hit as limits on the amount of traffic)

Why? Do you think that 192.168.0.0/23 is too bad for this? Or 192.168.0.0/22?
The efficency of this router could not be good enough but IT COULD be done.

So true.
I am too accustomed working with /24...