There is really so much failure in this post: crappy vendor, misunderstanding how PPP actually works (it requires no addressing at all), using "half bridge" (idiot term) instead of just using it properly. I swear people are even less informed than 20 years ago, it's very sad.
Seems to be a commonly accepted term for this purpose:
https://openwrt.org/docs/guide-user/network/wan/bridge-mode#...
Idiot majority does not make it correct. But that page makes it absolutely clear that apparently nobody understands how PPP actually works (hint: addressing is not PPP)