@calpy I'm not the support of the tplink, just a super fan of this company lol Not sure why this will happen, still thinking about the reason

@pilak Hi, Suppose your building1 has no VLAN setting. And suppose your router's IP is 192.168.0.1. Then you can consider adding an ER605 in building2, then connect the TL-SG3428XMP to the first WAN...

@Hooch I think your understanding is correct, when clients use the gateway's IP as DNS servers, they are used to resolve addresses. In fact, I have not set additional DNS server, I use the default...

@Tobias16 According to my understanding, This IP 10.0.1.0 should not be available, can you try to use your PC or other devices in the LAN to access your server to see if you can access it normally.Or...

@Family_AM Hey 1. I guess you set up DDNS because you use features such as port forwarding or remote access, right ? You can try to use this function with the domain name as well as the IP separately...

@jwaltrip I saw a similar article when I browsed the forum earlier, and I think you can refer to it. https://community.tp-link.com/en/business/forum/topic/521910