Lately, I have been unable to use TP-Link routers in situations where routers existing in the network has to be replaced, for the largest reason that sadly, TP-Link is the only mainstream manufacturer of routers (rack mount), that do not offer (at present) multi-lan configurations.

For example, I asked SMB support how to get multi-lan/vlan to work and was recommended to replace switches with managed ones. If I walking into a company and tell them the entire network has to be replaced (all the switches and a router) just to replace the existing failing router that has multi-lan configurations with TP-Link products where the router doesn't, would get me fired!  So sadly, what I have at one location now, is EAP225V3.1's an OC200 and a Cisco RV340...  The headaches I had with VLAN configuration with that router and their existing Cisco managed switch (and I believe it may be failing, unsure yet as the error count is high) was a lot of extra work.  Had they not had that managed switch, I wouldn't have had to LOCALLY manage it for the VLAN for the EAP225V3.1s (Guest network).  Had I been able to use the ER5120 (had it had full multi-lan support), it would have been a simpler configuration with less management requirements.

Most of the businesses I deal with, are under 200 employees and their networks are not "massive" and therefore require hardware capable of surviving Internet hacking and still provide multi-lan support.  The reason for the multi-lan also stems from isolating networks, as in Guest (192.168.10.0/24), Office (192.168.0.0/24), Cash (192.168.1.0/24), etc, the other reason is with Guest networks I need to be able to severely limit their ability to "Facebook", "Facetime", "Upload their life to the cloud" using different DNS services, where as on Office I would only block some of that, Cash would be isolated 100% so that wired devices can't see anyone on any subet, but the internet, by blocking all services on the LAN minus the ones used by the cash systems.  Some of the locations require 2 to 300 Guest wireless connections, to design this type of network with 1 lan would be itself a feat of configuration without a managed switch, which again, would require replacing the entire network and walking into any business to say that would be "we'll get back to you" type of response.

I wish to continue to sell TP-Link products, but having all the same ducks on the rack, makes it less quirky (and no I wasn't going for quacky).