I can’t hear anything from earpiece!

Please understand if my English sounds unnatural.

I’m the iphone 8 user from South Korea.

I think, after I upgraded my phone to iOS 11.0.2, I can’t hear anything from earpiece (receiver speaker). But I’m not sure coz I didn’t check right after upgrade.

When I call someone without earphones or speaker mode on, I can’t hear and only caller can. When I listen to music, it plays only through the bottom speaker. So I wanted to check certainly, I recorded with voice memo app and play. It played through the bottom speaker well. But when I tried to switch to earpiece mode, it didn’t change at all. It just stuck in speaker mode (with blue speaker symbol).

In Korea, iPhone 8 has not been released yet. So I can’t get any help or service. I bought it from Hongkong. Please help me. When I search about this, there are only “iOS 11.0.2 fixes earpiece problem.” And the Korean apple community couldn’t help me. So I am begging your helps with my poor English. I did hard reset, force reboot. It is not beacause of carrier coz I can call with my earphones or speaker mode. I hope it is not the hardware problem.

SUMMARY

1. My iPhone 8 sounds nothing from earpiece.

2. I think it starts after upgrade to iOS 11.0.2.

3. Carrier is not the problem.

4. I can’t get any help or service from apple in Korea.