The symptom: chat and API feel “randomly” slow while Clash is running

The failure pattern is frustrating because it looks like intermittent quality from the service itself. You enable Clash, pick a node that works for general browsing, open the DeepSeek web experience, and the interface paints: fonts load, the conversation chrome renders, maybe you even see a canned greeting. Then you send a prompt and the spinner runs long enough that you wonder whether the model is overloaded or your link is dying. Sometimes a hard refresh fixes it; sometimes switching nodes in your default “Proxy” group changes nothing at all. Developers see the same ambiguity in code: a script using the official base URL https://api.deepseek.com might succeed once, then throw a timeout on the next batch of completions, while curl from the same machine behaves differently depending on whether you remembered to export proxy variables.

That inconsistency is the key diagnostic clue. Truly broken exits are usually consistently broken. What looks like “DeepSeek is flaky today” is often a split-routing problem: one request leg goes through your intended international path, another hits a domestic shortcut or a catch-all rule, and a third never traverses Clash because the process is not proxy-aware. DeepSeek’s own infrastructure spans normal HTTPS sites, websocket-heavy chat transports, and API endpoints that share a certificate namespace but not identical traffic shapes. If your profile was tuned for a generic “foreign AI” bucket, it may omit a hostname the product actually uses, or it may classify an address in a way that collides with a large onshore rule-set. The fix is not more aggressive global proxying; it is explicit naming for DeepSeek so every leg shares one predictable policy group.

This article is intentionally narrower than a roundup of every generative AI vendor. If you need the broad pattern for ChatGPT, Grok, and friends, start with split routing for AI sites in Clash first, then return here for the DeepSeek-specific hostname stack and API client details that the general guide does not optimize for.

Why DeepSeek deserves its own section in your YAML

DeepSeek is not interchangeable with OpenAI or Anthropic at the DNS layer. The product pairs a consumer-facing site under the deepseek.com suffix with an API hostname api.deepseek.com that speaks an OpenAI-compatible HTTP surface. That similarity to OpenAI’s ergonomics tempts people to reuse the same policy group they already maintain for openai.com, but the domains do not magically inherit one another’s rules. A profile that pins OpenAI correctly can still send DeepSeek chat traffic through a default MATCH group that alternates between exits, or through a GEOIP-driven DIRECT path, depending on how community rule-sets classify the CDN addresses you hit.

There is also a process-level split. Browser tabs inherit the operating system proxy when your Clash GUI enables system proxy mode, so the web UI may look healthy even while a Python virtual environment or a Node script runs without HTTP_PROXY set and talks to api.deepseek.com on a naked path that bypasses Clash entirely. Conversely, TUN mode can make CLI tools transparently routed while the browser breaks if DNS and Fake-IP disagree. DeepSeek workflows therefore touch both halves of the problem—rules and runtime environment—more often than a casual “AI sites” bookmark set.

Finally, popularity matters for congestion and policy: when a model vendor spikes in public attention, shared exits and rate limits show up as timeouts that are easy to misattribute. Giving DeepSeek a dedicated DEEPSEEK group lets you attach a conservative health check, a failover order, or a low-latency node list without destabilizing unrelated traffic. You troubleshoot one dial instead of retuning your entire international stack every time a chat session misbehaves.

Hostnames to pin for the website, chat, and API

Start from the public surface area you can observe and document. The consumer product lives on hostnames under deepseek.com, including the apex and www, and commonly the chat subdomain chat.deepseek.com for the interactive application. Covering the registrable suffix with a single DOMAIN-SUFFIX,deepseek.com rule is the most maintainable default: it catches the landing pages, help content, authentication flows, and future subdomains the vendor adds without forcing you to fork YAML every quarter.

The developer API is explicitly hosted at api.deepseek.com. Inference clients—whether you call /v1/chat/completions with a bearer key or use an SDK that defaults to the OpenAI-compatible base URL—terminate TLS on that hostname. If your logs show sporadic DIRECT connections to this name while the browser uses a proxy, you do not need a second mystery rule; you need to verify shell environment variables or TUN coverage, because the name itself already fits the suffix rule once you implement it.

Modern web apps also pull static assets and telemetry from additional paths that may or may not sit on the same registrable domain. In practice, keeping deepseek.com as the primary anchor resolves the majority of user-visible failures. If your connection panel shows unexpected third-party domains during chat sessions, treat them as optional follow-ups: add narrow rules only when logs prove they require the same exit characteristics as the core product. Over-eager wildcarding of unrelated CDNs clutters the rule list and makes debugging harder, not easier.

If your organization routes mainland and international traffic differently, remember that suffix-based rules operate on the name before resolution completes in Fake-IP mode. The point is not to guess country tags for DeepSeek; the point is to ensure that whichever resolver path you use, the resulting connections are matched by a deliberate line that names DEEPSEEK rather than falling through to a GEOIP shortcut that made sense for domestic video sites but not for your model API.

Designing the DEEPSEEK policy group

Create a proxy group whose sole job is carrying DeepSeek-related traffic. Name it DEEPSEEK (or any label you will recognize six months later) and reference that label from every DeepSeek domain rule. A select group is enough for manual control; a url-test group helps when you want automatic failover among a handful of exits that all support long-lived HTTPS. Point health checks at a lightweight HTTPS target you are allowed to probe—many operators use the API host root or a static asset path—and keep intervals sane so you are not hammering the vendor while chasing latency.

Resist merging DEEPSEEK with unrelated “AI” buckets unless you truly want identical failover semantics. Mixing vendors in one group couples their outage stories: when a ChatGPT-specific node degrades, you do not want DeepSeek silently dragged along. Separation costs one extra group block in YAML; it buys independent tuning and clearer connection logs when only one product regresses.

A minimal skeleton compatible with mihomo-style profiles looks like this:

proxy-groups:
  - name: DEEPSEEK
    type: select
    proxies:
      - <your preferred exit node>
      - DIRECT

rules:
  - DOMAIN-SUFFIX,deepseek.com,DEEPSEEK
  # ... remaining rules below, with GEOIP and MATCH after explicit vendor lines

The DIRECT fallback is optional insurance when you deliberately test domestic paths; many users omit it to avoid accidental leaks. Whatever you choose, document the intent in a comment so future-you understands whether DIRECT is a trap door or a supported mode.

Rule order: keep DeepSeek above GEOIP and heavy rule-sets

Clash evaluates rules sequentially and stops at the first match. Profiles optimized for regional performance often insert aggressive GEOIP,CN,DIRECT lines or import community collections that classify large address blocks. Cloud front-ends for AI products frequently ride global CDNs whose addresses do not always align with intuitive geography in third-party data. The safe pattern is to place DOMAIN-SUFFIX,deepseek.com,DEEPSEEK near the top of your explicit vendor section, before any imported RULE-SET that might swallow the hostname first, and well before broad GEOIP shortcuts.

If you already subscribe to an “AI services” rule-set, open it once and verify whether deepseek.com appears and which group it targets. If the upstream classification disagrees with your intent, shadow it by repeating the suffix rule above the import. Shadowing is preferable to editing vendor files you do not own: your line wins on first match, and updates to the bundle will not silently revert your preference.

For a deeper explanation of how domain rules interact with Fake-IP and fallback logic, read Clash YAML: routing rules, proxy groups, and Fake-IP. The short version: explicit domain matches should win over geography guesses, but only if you actually write them that way in the ordered list.

API clients, SDKs, and why the browser can lie to you

The OpenAI-compatible ergonomics of DeepSeek’s HTTP API encourage developers to drop a base URL into existing tooling. That convenience hides the same proxy gap every CLI stack faces: libraries read HTTP_PROXY, HTTPS_PROXY, and NO_PROXY from the environment, not from macOS network preferences or Windows WinInet settings. A Jupyter kernel launched from an IDE, a systemd service, or a Docker container without injected env vars will connect “directly” from the perspective of the host network namespace even when Clash is listening on 127.0.0.1:7890.

Set the mixed port from your Clash GUI and export both uppercase and lowercase variants if your toolchain is picky:

export HTTP_PROXY="http://127.0.0.1:7890"
export HTTPS_PROXY="http://127.0.0.1:7890"
export NO_PROXY="localhost,127.0.0.1,::1"

On Windows PowerShell for a single session:

$env:HTTP_PROXY  = "http://127.0.0.1:7890"
$env:HTTPS_PROXY = "http://127.0.0.1:7890"
$env:NO_PROXY    = "localhost,127.0.0.1"

Replace the port with the value your profile actually binds. If only the browser works, run env | grep -i proxy in the same shell that launches your script: empty output means the fix is environmental, not nodal. For WSL2, remember the Windows host address is not loopback from the Linux namespace; follow WSL2 mixed-port routing when your API tools run inside Ubuntu while Clash lives on Windows.

Once env vars are consistent, the DEEPSEEK group governs which exit carries TLS to api.deepseek.com. If curl through the proxy succeeds but your SDK still fails, suspect library-specific overrides, corporate certificate inspection, or a container network namespace that bypasses the host variables entirely.

TUN mode when you want process-transparent routing

TUN mode lifts the burden of per-shell proxy configuration by intercepting traffic at the virtual interface layer. Any process that opens a TCP connection to api.deepseek.com will pass through Clash’s rule engine, including runtimes that ignore HTTP_PROXY. That is attractive for data science notebooks and background workers where maintaining environment parity is tedious.

The tradeoff is operational complexity. TUN requires elevated privileges, interacts with other VPN clients and corporate split tunnels, and surfaces DNS integration issues more aggressively than plain system proxy mode. On Windows, firewall prompts and routing table conflicts are common enough that we keep a dedicated troubleshooting walkthrough in Fix Clash TUN on Windows: routing, firewall, and stack conflicts. The DeepSeek domain rules themselves do not change between modes; only the mechanism that delivers packets to the Clash core does.

DNS, Fake-IP, and keeping names coherent

Fake-IP mode returns synthetic addresses for domain queries so Clash can defer resolution until it knows which rule matched. That works beautifully when every resolver hop cooperates. It fails mysteriously when a subprocess uses a DNS path that bypasses Clash while still trying to connect to a Fake-IP range it does not own. For DeepSeek, verify that chat and API hostnames are not stranded in a fake-ip-filter misconfiguration that sends some clients to real public resolvers while others stay inside the Fake-IP pool.

Also watch nameserver-policy: sending deepseek.com queries to a resolver that returns geographically surprising answers can make it look like “the node is wrong” when the IP you finally connect to was never the one your exit expects. Align upstream DNS with the same philosophy as your rule list: intentional, documented, and testable.

Verification: logs first, curl second, node hopping last

Open your client’s live connection view and reproduce a failure. You should see each DeepSeek hostname associated with the DEEPSEEK group, not with GEOIP or a generic Proxy bucket you forgot to update. If the log shows DIRECT for api.deepseek.com, scroll upward in YAML until you discover which earlier line should have matched; fix order or coverage before you blame the service.

For a focused TLS test that does not require exposing API keys, use curl with verbose output:

curl -v --proxy http://127.0.0.1:7890 https://api.deepseek.com/ 2>&1 | head -40

A completed handshake with an HTTP response code from the vendor—even a 404 on the bare path—means routing and TLS are fundamentally sound. Connection resets point to the exit or middleboxes on the path. Immediate refusal to connect means the proxy port or bind address is wrong for the namespace you run curl from.

Developers who already solved similar patterns for other vendors can borrow the same verification mindset from Anthropic API split routing for Claude Code: the hostname list differs, but the log discipline does not.

Quick symptom map

Intended use

Proxy configuration is about choosing lawful, transparent paths for traffic you already have permission to send. It does not grant license to violate DeepSeek’s terms, bypass account restrictions, or circumvent workplace acceptable-use policies. Treat this guide as network hygiene for legitimate developers and end users who need stable HTTPS to documented endpoints.

Closing: name the lane, then trust the logs

DeepSeek’s blend of a public web product and an OpenAI-compatible API multiplies the ways a Clash profile can silently do the wrong thing. A single DOMAIN-SUFFIX,deepseek.com,DEEPSEEK line is small on disk but large in impact when it sits above geography shortcuts, and pairing it with honest shell proxy settings closes the gap between “browser works” and “SDK works.” Once the lane exists, your connection log tells the truth faster than superstition about which node “feels lucky.”

Compared with opaque clients that hide routing decisions, Clash-family cores show exactly which rule matched and which group carried the flow—the kind of transparency that turns a vague timeout into a configuration fix you can repeat. When you want a client that pairs readable traffic views with modern mihomo routing, start from the download page to keep installers and docs aligned. → Download Clash for free and experience the difference.