Strange router behaviour

Six months ago I bought TP-Link router and when I coected it to my PC I was getting I-Ball interface. So I had to change router ip address and was able to use TP-Link normally. My friend told me that it happens if you used other router in past. After couple of months I bought new PC and have never coected any other router to my PC.

Today my inteet coection was discoected so I tried detecting network type. Usually my coection is PPPOE but today it was Dynamic IP, so I changed my coection type to Dynamic IP and saved it. After few seconds I was coected to inteet. But at 192.168.1.1 I was getting D-Link interface which I have never coected to my PC to even old PC. Plus at 192.168.0.1 now I am getting TP-Link interface and I can use it normally.

I checked settings of this D-Link router and found that it has DHCP enabled with around 10 users coected to it. So I assume that someone inexperienced haven't setup their router correctly.

But what I find weird is that I am accessing some exteal interface on my PC as if it is in my home. Other strange thing is that all users through my isp are on same public ip but when I use this dynamic IP coection I am getting different public ip.

Important thing to note is that I have never coected different router to this pc or I don't have any other router in my home. I find this whole situation strange.