You were correct, I have a TP-Link router:
$ nslookup tplinklogin.net
Server: 192.168.1.1
Address: 192.168.1.1#53
Non-authoritative answer:
Name: tplinklogin.net
Address: 192.168.1.1
---
An external request:
$ nslookup tplinklogin.net
Server: 2001:4860:4860::8844
Address: 2001:4860:4860::8844#53
Non-authoritative answer:
Name: tplinklogin.net
Address: 103.224.212.249