Unable to access to webfig(port 80) throgh VPN client

Hello,
Thank you for accepting me in this community.
I apologize in advance for my bad English.
I explain my situation:
I’m using a MikroTik HAP RB941-2nD TC-lite in
VPN-client mode.
It is connected to the Internet thanks to another router through the “Internet” port.
I have also connected via the LAN port a PC and another device (a converter TCP / IP to RS232).
The VPN server is on my linux server.
I also created another VPN-client user on a different Internet network in order to connect through mikrotik hap lite to tcp / RS232 converter.
I had no problem in creating the vpn.
I reach without problems the converter managed to enter in the web interface
through a NAT rule, redirecting 8080 on 80 of the converter on the VPN interface created on mikrotik hap lite.

THE PROBLEM is the following:
I am not able to access the web interface of mikrotik (webfig to port 80 by default) from the VPN-client external to the network on which are the mikrotik and converter.

you can help me??

If you’re using VPN, why not simply route the IP range across the VPN instead of using NAT?