I have connected 4 antminers to 1 TP link router and that router is connected to modem.
You should look over 192.168.1.X and 192.168.0.X.
This can be done by changing your router IP address. That way you'll be able to catch your miners that aren't in your DHCP IP Address Range.
Can you please explain me a little more? What is x supposed to be and what am I supposed to change my IP to?
Sure, you can connect to your router by typing either 192.168.1.1 or 192.168.0.1 (depends on your router factory settings).
My guess is that your miners aren't in your DHCP range. Which means the devices you connect to your network are expected to be within 192.168.1.1 and 192.168.1.99, but your miners are set to something like 192.168.0.XX.
What I mean when I say "X" is variable, any number between 0 and 255.