@SoapyPotato Your switch's settings are correct. You already did the test to verify that VLAN4 can work. When you connect SSID #4, did you get the IP address that Router "Zulu" assigned? If you can...

@NikosK If you are convenient, you can disconnect WAN1 temporarily. Then check if the DNS will fail all the time after disconnect WAN1. If yes, we can confirm WAN2 link has problem. Then check the...

@ykzamorpheus Firstly, make sure you did not use link backup function. Then you can try to exchange the cable for WAN1 and WAN2. Check if the problem only happens on WAN2. And you can try to upgrade...

@Burczymucha That's strange. Maybe you can check the ARP table for T2600G-28TS and gateway. Make sure they both have the correct ARP information. If you could use wireshark, you also can use it to...

@AdrianJC As I knew, TP-Link has not switch that support cloud yet. But this is a trend. I think they will release cloud based switch.

@Bleami Hi If you follow that TP-Link FAQ, it's normal that three departments can communicate with each other. Because it has L3 interface for each VLAN, so they can communicate with each other...