@papergion 

Hey

Honestly not sure what the answer is here, but one thing does pop to my head..

If you need to ask how many port forwards this can handle, then you either have too many port forwards... or need to consider a much more business grade device. 

If you are creating port forwards all over the place, this is a MASSIVE security weakness and you should reconsider this.  However if you are running 15/ 20 / 50 servers in the background, why are you even considering this device as a valid option?   You should be looking at something much more robust.

Port forwarding should be the very last resort as this totally bypasses your firewall.   Also remember you have DMZ which is almost the same thing.

  @Philbert

hi

i know what is port forwarding.

recently i returned a "Tenda" modem because i found it can only forward 8 directive. and i need at least 14, used for my experimental devices such raspberry, orange and so on.

thank for your answer