In your video you also use the device ip, but in your case the router have different lan ip.
Then you don't have the same ip.
We test to connect two RUT240 witch have same Lan IP and they have 1 plc eatch with same IP
If we only connect one no problem to connect.
But if both is connected we have two plc with same IP.
In this case nothing happends if we connect, just no connection