We have an Apple-centric office and as such we rely on Bonjour (mDNS) for auto-discovery of things like printers, AirPlay targets, and pseudo-servers (e.g. exchanging files between desktop computers).
I just installed a TP-Link T1600G L2+ switch as our core switch as a step to help manage the network as we embrace IPv6 and the proliferation of Internet-connected devices. (Eventually I want to be able to have guests sign into our WiFi, access the internet, and also access the Apple TV/AirPlay in our conference rooms, but not access any of our other internal resources, for example, but I understand that will take a full Level 3 router (on order), and that will be a different post if I run into trouble.)
For now, I just installed the T1600G, plugged the WAN router/NAT/DHCP server, all our dumb L2 switches and wireless APs, our main servers, and our IoT devices into it (intending to isolate the APs and IoT stuff via VLANs later). But I haven't even gotten as far as setting up a VLAN and already I've broken something.
In particular, I've found that enabling the T1600G "DoS Defend" protection, firmware version "1.0.3 Build 20160412 Rel.43154(s)", blocks Bonjour somehow, but I can't figure out how or why or what to do about it (other than leave the DoS protections turned off). I'm not even sure how to diagnose the problem because I don't know how to force a Bonjour advertisement to be issued.
Is there something about IPv6 multicast that looks like IPv4 DoS attack?
I called TP-Link business technical support. They didn't know what Bonjour was and hung up on me.