Access SXT through hAP lite

RouterOS Beginner Basics
1

I have a SXT providing internet to a hAP lite that is used to provide wifi access for the client devices. The hap is on 192.168.88.xx and the SXT is on 192.168.188.247 for internet. How can I access the web interface of the SXT so I can change the settings. Going through the hAP?

2

hAP and SXT are connected via ethernet.
But what address is used on both connecting ports ?

It should be as simple as adding a route to 192.168.188.0/24 and use address of SXT.

EDIT: I suppose hap is acting as real router with DHCP and NAT ?
Why not move everything in 1 subnet ? Much easier.