Amplifi HD with HEX

RouterOS Beginner Basics
1

Gentlemen,
First of all, Apologies for the long and poorly drafted post.
Please help me, I am not very well experienced with terminals and networking but can understand and follow instructions and concepts if explained in an easy manner.
I have the following setup.

A fiber modem/router (huawei brand) from my ISP connected to Mikrotik HEX connected to Amplifi HD.

  • Nothing connected on lan interface of the Fiber modem except Mikrotik ( I wanted to get rid of it, but it seems they manage my ISP account through it, plus I don’t have a router to receive a fiber optic connection)
  • Mikrotik does all the DHCP, DNS, VPN, Firewalls etc.. ( I still need to add port forwarding in the fiber modem in special cases because I understand mine is a double NATd situation) and only has my main PC connected on LAN2 and Amplifi HD connected on LAN1.
  • Amplifi HD does not do DHCP for the main network , but has a guest network that’s rarely on ( I assume it blocks my other local resources like the main PC , I hope !!) . All my wireless devices are connected to the Amplifi HD. I also have an Arlo base station connected to the LAN on Amplifi, if it is relevant and important to know.
  • There are some other things in my network as well… like smartthings hub on amplifi lan, samsung smart tv on amplifi lan.

Now my problem is , from my wireless devices I can access my PC with ip address, which is wired directly to the HEX, But from my PC I cannot see my phone.

This is important for me for some things like,

  • sometimes I want to connect to my note8 with sidesync from my PC.
  • or lets say I want to run a network monitoring tool on my PC for the wireless network from Amplifi to send alerts whenever devices connect/disconnect( do you know a good one).
  • Please guide me how can I make devices from amplifi (except guests) and devices from Mikrotik see each other completely as if they were in the same lan.
  • Another reason for this is so I can control bandwidth for some particular users ip based/MAC based whatever is possible.

Thanks a lot in advance !!!