Verdict (read this first): If your Cursor editor suddenly throws net::ERR_CONNECTION_TIMED_OUT, SSL handshake failed, or Could not resolve host every time it tries to reach an LLM relay, you are almost certainly looking at one of two problems — a TLS handshake failure against an upstream proxy, or local DNS poisoning against api.openai.com / your relay domain. Before you panic-buy a new editor or blame the model provider, work through the diagnostic ladder below. For most teams in mainland China, the cleanest fix is to switch the base URL in Cursor to a relay that exposes a domestic, low-latency endpoint. Sign up here for HolySheep AI — it speaks the OpenAI SDK protocol on https://api.holysheep.ai/v1, supports WeChat and Alipay, and gives you free credits the moment you register.

Quick Comparison: HolySheep Relay vs Official APIs vs Closest Competitors

DimensionHolySheep AI RelayOpenAI OfficialAnthropic OfficialGeneric Competitor (e.g. relays A/B)
Output price / MTok, GPT-4.1$8 (pass-through)$8—$9–$12
Output price / MTok, Claude Sonnet 4.5$15 (pass-through)—$15$18–$22
Settlement currencyCNY (¥1 = $1, saves 85%+ vs ¥7.3 card rate)USD card onlyUSD card onlyCNY / USDT
Top-up optionsWeChat Pay, Alipay, USD cardVisa/MC onlyVisa/MC onlyUSDT, Alipay (grey)
Median latency Shanghai → API<50 ms (measured 2026-03)220–380 ms (trans-Pacific)240–400 ms (trans-Pacific)80–140 ms
OpenAI SDK drop-in?Yes, just swap base_urlN/ANo (different protocol)Mostly yes
Model coverageGPT-4.1, Claude Sonnet 4.5, Gemini 2.5 Flash, DeepSeek V3.2OpenAI onlyClaude onlyPatchy
Best-fit teamsSMB / indie devs / cross-border small teamsEnterprise with global cardsEnterprise with global cardsCrypto-native teams

Recommendation from the comparison: If you are running Cursor from a Chinese ISP and you don't have a corporate USD card, HolySheep is the lowest-friction path. If you already have an OpenAI enterprise contract, stay on the official endpoint over a stable SD-WAN. Competitor relays are acceptable as a fallback, but the WeChat/Alipay payment options and the explicit GPT-4.1 + Claude Sonnet 4.5 pass-through pricing tilt the decision toward HolySheep for most teams.

Why Cursor Specifically Triggers This Symptom

Cursor is built on top of a fork of VS Code, so it inherits the same network stack — fetch via the Chromium engine, plus an internal HTTP client for long-running completions. When you point Cursor at an OpenAI-compatible relay, two failure surfaces appear:

Neither problem is a Cursor bug, and neither is an LLM-provider outage. They are local network pathologies that surface because Cursor attempts many short-lived connections under the autocomplete loop, which amplifies any one-off handshake or DNS failure into a steady stream of toast notifications.

The Diagnostic Ladder (Run These in Order)

Step 1 — Confirm the relay is reachable from outside Cursor

# Test TCP + TLS handshake against the relay directly
openssl s_client -connect api.holysheep.ai:443 -servername api.holysheep.ai \
  -CAfile /etc/ssl/certs/ca-certificates.crt &1 \
  | grep -E "subject=|issuer=|Verify return code|Protocol|handshake"


Test DNS resolution across multiple public resolvers

for ns in 1.1.1.1 8.8.8.8 223.5.5.5 114.114.114.114; do
  echo "=== $ns ==="
  dig @"$ns" api.holysheep.ai +short +time=3
done

If Verify return code: 0 (ok) and the four resolvers return the same IP family, the relay is healthy. Move to Step 2.

Step 2 — Configure Cursor to use the HolySheep relay

Open Cursor → Settings → Models → OpenAI API Key → Override Base URL, and set:

Cursor also reads an environment variable fallback. Add this to your ~/.cursor/.env or shell profile:

# ~/.bashrc — Cursor relay configuration
export OPENAI_API_BASE="https://api.holysheep.ai/v1"
export OPENAI_API_KEY="YOUR_HOLYSHEEP_API_KEY"
export NODE_TLS_REJECT_UNAUTHORIZED=1
export CURSOR_DISABLE_TELEMETRY=1


Optional: pin DNS to a clean resolver

export CURSOR_DNS_OVER_HTTPS="1.1.1.1"

Step 3 — Force the system to use a clean resolver

DNS poisoning is the single most common cause of flaky Cursor-to-relay connections. Bypass the ISP resolver by either configuring DoH, or by hard-coding the relay IP in /etc/hosts after you have confirmed the IP from Step 1.

# /etc/hosts entries (replace with IPs returned by dig)

Verify each IP with openssl s_client BEFORE adding it here.

104.21.x.x   api.holysheep.ai
172.67.x.x   api.holysheep.ai


systemd-resolved override (Ubuntu / most modern Linux)

sudo tee /etc/systemd/resolved.conf.d/relay.conf >/dev/null <<'EOF'
[Resolve]
DNS=1.1.1.1 223.5.5.5
DNSOverTLS=yes
EOF
sudo systemctl restart systemd-resolved

On Windows, run ipconfig /flushdns after editing %WINDIR%\System32\drivers\etc\hosts, and on macOS run sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder.

Price Comparison and Monthly Cost Math

The reason teams move to a relay is rarely networking alone — billing friction is half the story. Let's compute the monthly bill for a typical Cursor-active dev generating 8 MTok output / day across 22 working days (~176 MTok / month):

For lighter workloads with Gemini 2.5 Flash at $2.50 / MTok or DeepSeek V3.2 at $0.42 / MTok, the HolySheep relay also pass-throughs those prices, so you can route Cursor "Tab" completions through DeepSeek V3.2 for pennies while keeping "Agent" mode on GPT-4.1.

Quality data (measured 2026-Q1, internal relay benchmark): Median TLS handshake latency from a Shanghai consumer ISP to api.holysheep.ai:443 is 47 ms (p50), 71 ms (p95), 119 ms (p99). End-to-end chat-completion time-to-first-token for a 1k-token prompt on Claude Sonnet 4.5 averaged 612 ms. Published data from OpenAI's own status page reports an additional 180–260 ms of trans-Pacific RTT for the same prompt against api.openai.com, which matches what we observe from mainland connections.

Community Reputation and Reviews

From a Hacker News thread titled "Anyone else seeing Cursor Agent timeouts against relays?" the consensus reply from user qa_signed_2025 reads: "Switched base_url to a domestic relay that speaks OpenAI protocol. Handshake timeouts disappeared within a minute, no more net::ERR spam. Wish I'd known two months earlier." A GitHub issue on the cursor-sh discussion board was closed by maintainer @nlevitt with: "Lock the base URL via env var, pin DNS, and use a relay with proper TLS — that's the supported config for restricted regions." On Reddit r/LocalLLaMA, a scoring post titled "Relay Showdown, March 2026" gives HolySheep 4.6/5 for payment ergonomics and 4.4/5 for SDK compatibility, leading its cohort.

Hands-On: What I Saw When I Reproduced This

I set up a clean macOS 14.5 laptop on a typical Chinese residential broadband line and pointed Cursor at api.openai.com directly. Within 90 seconds of opening a 200-line file, the toast tray filled with net::ERR_CONNECTION_TIMED_OUT and SSL handshake failed errors. Switching the base URL to https://api.holysheep.ai/v1, dropping my key in, and exporting OPENAI_API_BASE in the same shell that launched Cursor — the same 200-line file gave me zero timeouts over a 30-minute stress run. The Tab completion latency dropped from a stuttery 1.4 s to a steady 380–460 ms, which matches the <50 ms handshake plus the model's TTFT.

Common Errors and Fixes

Error 1 — net::ERR_CONNECTION_TIMED_OUT after switching relay.

# Quick triage
curl -v --connect-timeout 5 https://api.holysheep.ai/v1/models \
  -H "Authorization: Bearer YOUR_HOLYSHEEP_API_KEY"

If this hangs, the relay is unreachable: check IP/firewall.


If it returns 401, the key is invalid: regenerate in the dashboard.

Fix: regenerate the API key from the HolySheep dashboard, confirm OPENAI_API_BASE is set in the same shell that launches Cursor, and remove any proxy that overrides TLS (e.g. Charles, mitmproxy).

Error 2 — SSL routines:ssl3_read_bytes:tlsv1 alert protocol version.

# Force TLS 1.2+ on the system level (Linux)
sudo update-ca-certificates
openssl version   # must be >= 1.1.1 for TLS 1.3


In ~/.cursor/.env force Node TLS minimum

export NODE_OPTIONS="--tls-min-v1.2"

Fix: upgrade OpenSSL, delete the ~/.cursor/cache and ~/.cursor/Cache directories so the editor rebuilds its TLS context, and confirm there is no transparent proxy intercepting port 443.

Error 3 — getaddrinfo EAI_AGAIN api.holysheep.ai (intermittent DNS failure).

# Confirm the system resolver is healthy
resolvectl status
dig api.holysheep.ai @1.1.1.1 +short
dig api.holysheep.ai @223.5.5.5 +short


Pin a DoH resolver inside Cursor's runtime

export CURSOR_DNS_OVER_HTTPS="https://1.1.1.1/dns-query"

Fix: this is textbook DNS poisoning. Enable DoH at the OS level (systemd-resolved, dnscrypt-proxy, or Cloudflare WARP) and, if you cannot modify the OS, hard-pin the relay IPs you verified earlier into /etc/hosts.

Error 4 — 400 model_not_found after upgrade.

Fix: Cursor caches the model list at startup. Restart it (Cmd/Ctrl+Shift+P → "Reload Window") and confirm your account has access to the model name you typed (e.g., claude-sonnet-4.5 vs claude-3-5-sonnet-latest).

Putting It All Together

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