China Telecom CGNAT Home Network Analysis | Generated by AI
Good, now you’re on your HOME network. Here’s the analysis:
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HOME NETWORK — China Telecom Fiber ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Local IP: 192.168.22.5 Gateway: 192.168.22.1 (your home router) Subnet: /24 (255.255.255.0) Public IP: [REDACTED] (Shenzhen, AS4134 CHINANET)
Ping to baidu: avg 23ms, jitter 24ms ← good Ping to gateway: avg 16ms (first hop 69ms cold start, then 3ms)
Download: ~413 KB/s (~3.3 Mbps) Upload: ~380 KB/s (~3.0 Mbps)
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DOUBLE NAT — YES, CONFIRMED ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
The traceroute proves it:
Hop 1: 192.168.22.1 ← NAT #1: your home router Hop 2: 172.16.3.252 ← NAT #2: ISP CGNAT gateway Hop 3: ** * (hidden) Hop 4: 14.147.195.133 ← public backbone … Hop 9: 14.29.117.178 ← near destination
172.16.3.252 is a PRIVATE IP (172.16.0.0/12 range). That’s China Telecom’s CGNAT — your traffic goes through TWO NAT layers before hitting the public internet:
You (192.168.22.5)
→ Home router (192.168.22.1) [NAT #1]
→ ISP CGNAT (172.16.3.252) [NAT #2]
→ Public IP [REDACTED]
Why does China Telecom do this?
- IPv4 address exhaustion — not enough public IPs for everyone
- They share one public IP across many customers via CGNAT
- This is standard for Chinese residential broadband since ~2015
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WHAT DOUBLE NAT MEANS FOR YOU ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
- No inbound connections: port forwarding on your home router won’t work because CGNAT blocks it upstream anyway
- No self-hosting from home (web server, SSH, etc.)
- VPN hosting from home won’t work
- P2P games/apps may have issues
- Normal browsing, LLM APIs, dev work: totally fine
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COMPARISON: HOME vs EARLIER HOTSPOT ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Home (fiber) Hotspot (4G/5G) ───────────────────────────────────────────────────────── Ping avg 23ms 215ms Ping jitter 24ms 341ms Packet loss 0% 20% Download 3.3 Mbps 2.3 Mbps Upload 3.0 Mbps 0.5 Mbps NAT layers 2 (router+CGNAT) 3 (iPhone+router+CGNAT) Gateway ping 3ms N/A
Home is clearly better — 10x lower latency, 6x less jitter, 6x faster upload. But both go through CGNAT.
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NOTE: Your home bandwidth (3.3 Mbps down) seems low for fiber. Could be Wi-Fi negotiation at a low rate. If you connect via Ethernet you’d likely see 100+ Mbps. The bottleneck is probably your MacBook’s Wi-Fi link speed, not the fiber itself.