AFP is blocked on my RAX200

I have a Netgear RAX200 router and a bunch of Macs connected to it. I want to use AFP for file sharing between my computers but it doesn't work. It used to work fine with my old Asus router with DD-WRT. SMB, SSH and VNC work fine between my machines. I can also telnet between them on port 548 (the port AFP uses) but when I try to connect using AFP the connection fails. I use no firewalls. My conclusion is that the router somehow blocks AFP. Is that so? How do I "unblock" AFP?