If you route Google or Gemini traffic through Cloudflare WARP, one of the more confusing failures looks like this:

HTTP 400
FAILED_PRECONDITION
User location is not supported for the API use.

What makes it confusing is that WARP can still report Connected, the Gemini web app may still work, and the rest of your proxy stack can look completely healthy. In my case, the failure showed up in another client backed by Gemini while the normal web experience kept working.

That combination makes it tempting to change everything at once: Xray routing, Nginx, Cloudflare DNS, the VLESS entry point, even the Google account. The useful fix was much smaller. I first checked the actual WARP egress seen by the destination, reconnected WARP, compared the before/after egress, and then tested the client again.

This post assumes a setup where WARP runs as a local SOCKS5 proxy on the server and Xray sends only selected Google or Gemini TCP traffic through it. Your public entry point can still be Cloudflare, Nginx, and VLESS/WS. The important part is keeping ingress and egress separate in your head.

Check the last hop, not the VPS origin IP

The traffic path I care about looks roughly like this:

client
  ↓
Cloudflare / Nginx / Xray
  ↓
Google / Gemini traffic
  ↓
127.0.0.1:40000
  ↓
Cloudflare WARP
  ↓
Gemini

The easy mistake is to keep looking at the VPS public IP. That is the server’s origin address. Once the Gemini request is actually routed through the WARP SOCKS5 outbound, the destination should see the WARP egress instead.

Cloudflare’s WARP documentation makes the local-proxy behavior explicit: only applications or traffic configured to use the local HTTPS/SOCKS5 proxy are sent through WARP. Everything else keeps using the normal connection. That is why I prefer to test the SOCKS5 endpoint directly instead of inferring the result from a browser session or from warp-cli status alone.

The first command I run is:

curl -s --socks5-hostname 127.0.0.1:40000 \
  https://www.cloudflare.com/cdn-cgi/trace \
  | grep -E '^(ip|loc|warp)='

A healthy result looks roughly like:

ip=<warp-egress-ip>
loc=US
warp=on

Those three fields answer different questions:

• warp=on confirms that this request actually traversed WARP.
• ip= is the egress address the destination sees and is the value worth recording.
• loc= is a useful geolocation clue, but it is not proof that every Google or Gemini backend will accept the request.

That last point matters more than it sounds. Developers have reported cases in the Google AI Developers Forum where VPS traffic from a nominally supported country still received User location is not supported. So a result such as loc=US or loc=CA is useful evidence, but not a guarantee about Google’s internal IP classification.

The recovery path I use: record, reconnect, compare

If the WARP proxy is healthy and the error clearly points at location or eligibility, I do not start by changing Nginx or Xray. I make one small change first:

echo "=== BEFORE ==="
curl -s --socks5-hostname 127.0.0.1:40000 \
  https://www.cloudflare.com/cdn-cgi/trace \
  | grep -E '^(ip|loc|warp)='

warp-cli --accept-tos disconnect
sleep 5
warp-cli --accept-tos connect
sleep 10

echo "=== AFTER ==="
curl -s --socks5-hostname 127.0.0.1:40000 \
  https://www.cloudflare.com/cdn-cgi/trace \
  | grep -E '^(ip|loc|warp)='

In the incident that prompted this post, the reconnect produced a different shared WARP egress while warp=on stayed healthy and the location signal remained in a supported region. The client that had been returning the location error worked again after that change.

That result is useful, but I would not overstate it. It tells me the previous WARP egress was one of the triggering factors. It does not tell me that a specific WARP address is permanently “bad,” and it does not reveal how Google’s internal eligibility or geolocation systems classify traffic.

If the egress does not change after one reconnect, I may try once more. What I do not use as a normal IP-rotation method is:

warp-cli registration delete
warp-cli registration new

WARP registration state and the shared public egress are not a one-to-one mapping. Recreating the registration does not guarantee a new egress and adds another moving part to a node that may otherwise be healthy.

The troubleshooting sequence I now keep is intentionally boring:

verify the WARP SOCKS5 endpoint
        ↓
record ip / loc / warp
        ↓
disconnect / connect
        ↓
record the egress again
        ↓
egress changed → retest Gemini / the client
        ↓
still failing → inspect routing, IPv4/IPv6, DNS, or upstream classification

The advantage of this order is that each step changes one thing. If your ingress is already stable, a FAILED_PRECONDITION response is not a good reason to simultaneously edit Nginx, VLESS, Cloudflare DNS, and Xray routing. The more layers you change, the harder it becomes to know what actually fixed the issue.

There is also an important product boundary here. Standard WARP is not a deterministic residential proxy pool, and Cloudflare explicitly says WARP is not designed to let you pretend to access the Internet from another country. You cannot ask regular WARP for a specific city, a specific public IP, or a guaranteed new address on every reconnect.

If you genuinely need a fixed, dedicated egress that can be allowlisted, Cloudflare’s answer is Dedicated Egress IPs under Zero Trust Enterprise. Those are static addresses assigned exclusively to the account and tied to specific Cloudflare data centers. That is a very different capability from the shared egress you get from normal WARP.

For a solo developer, an occasional Gemini classification problem usually does not justify jumping straight to enterprise egress. But the distinction is useful because it keeps the architecture honest: use reconnect-and-verify as a troubleshooting tool; use a real dedicated-egress product when the requirement is stable identity.

I now split these incidents into two buckets. If the WARP SOCKS5 endpoint itself is broken, I troubleshoot WARP service state and the local proxy. If SOCKS5 works, warp=on is present, and Gemini still returns a location error, I focus on the egress address, protocol path, and upstream classification before touching the ingress stack.

If you are also consolidating multiple AI tools behind infrastructure you control, How to Proxy Codex with CLIProxyAPI: Docker Deployment and Client Setup is a natural companion. That post is about building a reusable AI entry point; this one is about keeping the last-hop egress diagnosable once selective routing is in place.