Problem GL-MT300N with LTE Modem Huawei E3372

I changed the GL Lan to something else from 192.168.8.10 (another IP than 192.168.8.1)

But

I still can’t access the E3372 hilink modem status from 192.168.8.1 after using tether from tethering tab.
But tethering works perfectly.

Why?

I’m using GL-AR150

Powered by LuCI openwrt-18.06 branch (git-18.196.56128-9112198) / OpenWrt 18.06.1 r7258-5eb055306f

Please advise
Thanks in advance.