I just switch to Oreo Beta yesterday and it's a complete disaster, here's the problems:
1. Mobile data no longer works, I cannot go to Internet while I'm on the road. Factory reset the phone / reset APN / swapping sim card slots, changing sim card doesn't solve the problem
2. Looks like the phone can only connect to 3G network now, previously I can always connecte to 4G / LTE
3. The recovery mode (power + volume up) key are no longer functioning. I can't enter recovery remove
4. Downgrading back to Android N and all the problem above remains
I will have to take the phone for warranty service.
A little update, after rebooting multiple times trying to hold the volume up + power key, the 4G / H+ / LTE network become available suddenly after initial setup (on Android Nougat).
Now I'll OTA to Orea Beta and try again.
Still fail in Oreo Beta, it was showing 4G once, immediately after boot, but there's no Internet access, rebooting and then it only shows 3G and also no Internet access.
Confirmed that there should be problem with APN / 4G / HSPA+ / LTE, Internet connection via mobile network is almost impossible.
Restoring to Android Nougat will not work initially, but after "resetting APN", the phone appears to down something from Google Play, then after a reboot, H+ sign is shown and mobile network works.
Please make sure to address this issue when you launch the Oreo.