diff --git a/backend_api_python/env.example b/backend_api_python/env.example
index 12657ff..7e12e35 100644
--- a/backend_api_python/env.example
+++ b/backend_api_python/env.example
@@ -200,10 +200,14 @@ SMTP_USE_TLS=true
 SMTP_USE_SSL=false
 
 # =========================
-# Proxy (optional)
+# Proxy (optional — required for Binance/Coinbase OHLCV in many CN networks)
 # =========================
-# PROXY_URL=socks5h://127.0.0.1:10808         # local
-# PROXY_URL=socks5h://host.docker.internal:10808  # Docker
+# CCXT reads PROXY_URL for api.binance.com / exchange REST calls. System VPN does
+# NOT apply inside Docker — set this when logs show "binance GET ... exchangeInfo" failures.
+# Clash: enable "Allow LAN", use HTTP port (often 7890). Docker Desktop on Windows/macOS:
+# PROXY_URL=http://host.docker.internal:7890
+# PROXY_URL=socks5h://127.0.0.1:10808              # backend run directly on host
+# PROXY_URL=socks5h://host.docker.internal:10808     # Docker + Clash SOCKS
 PROXY_URL=
 
 # Outbound HTTPS to exchanges when using PROXY_URL (especially SOCKS). If you see
@@ -386,7 +390,8 @@ DATA_SOURCE_RETRY_BACKOFF=0.5
 FINNHUB_API_KEY=
 FINNHUB_TIMEOUT=10
 FINNHUB_RATE_LIMIT=60
-# Public crypto OHLCV/ticker (no API keys). binance supports BTC/USDT; coinbase uses USD pairs and is often blocked in CN.
+# Public crypto OHLCV/ticker (no API keys). binance supports BTC/USDT.
+# In mainland CN / Docker without outbound access to api.binance.com, set PROXY_URL above.
 CCXT_DEFAULT_EXCHANGE=binance
 CCXT_TIMEOUT=10000
 AKSHARE_TIMEOUT=30