LMS-uPnP on the PC with 2 network interface

[maple4062]

I installed LMS on the PC that have two network interfaces. This PC, which OS is ubuntu, also built to serves as router,
Purpose of this setting is to set the ip address of HQplayer static and to stop various unrelated packets flowing into HQplayer through the network.

Now, Music library of LMS takes the data from /mnt/Music (ie. the mount point of NAS in the 172.xx.70.0/16 network which is connected to enp1s0 (172.xx.70.10), WAN interface.)
And the HQplayer, the player/renderer is connected to enp2s0, LAN interface of this PC (192.168.100.1).
IP address of HQplayer is 192.168.100.20.
As this PC serves as router, LMS can access both WAN and LAN interface, I supposed that NAS could be mounted and LMS and HQplayer could be controlled in 172.xx.70.0/16 network.
But uPnP bridge does not seem to find HQplayer in 192.168.100.0/28 network.

Is not there any way to solve the issue?

I guess setting the "Network binding and port" may solve this issue, but do not understand how to set this cell. (seems to be "192.168.100.1|enp2s0 :8088"?)
What is to be input in the cell of LMS port?
--LAN interface of the PC is enp2s0 and the IP address of the interface is192.168.100.1, and HQplayer use port 8088--

Any advice is highly appreciated.