Recently, I noticed some changes when logging into my router's backend. The obtained IP address started with 10, which is a private IP address. As a result, Stun detection no longer works. A few months ago, our local internet service provider, China Telecom, changed its bridging settings, and all IP addresses became public. Stun detection identified the NAT as type 1. I suspect that this is due to a bug in China Telecom's 0-narrow-band and 29+narrow-band connections, which caused a surge in users. Using public IP addresses is convenient, and we enjoyed this setting. In contrast, our mobile internet service provider changed its bridging settings and yet had public IP addresses. Stun detection identified the NAT as type 1 as well. This phenomenon seems strange.