Router DNS Rerouting, How to Exploit Router Wan Acces.

Hi there people!

I've been visiting this site 2015, and learned so much, but now I have a problem I cannot figure out how to solve.

I'm able to do man in the middle attacks with MITMf and BEEF, can create a backdoor that works over WAN too, but I cannot think of resolving my router wan acces.

Let's say I have acces to a remote managed router over the internet. What can I do with the acces?

How can I reroute the traffic from there and use mitm attacks or just monitor the traffic with wireshark.

My goal here is to create a persistent backdoor by accessing the remote router and than monitor the traffic, reroute the devices to certain domains etc.

Thanks in advance.