Hey! I noticed your Railway URL is connect-production-ba24.up.railway.app but your CNAME is pointing to 007tej75.up.railway.app - those don’t match. Your CNAME should point to the same subdomain as your Railway service URL. Try updating your DNS to point to connect-production-ba24.up.railway.app instead. If that’s intentional (like pointing to a different service), then there might be a routing issue on Railway’s end and you’ll need staff to check the proxy config for those request IDs you provided.​​​​​​​​​​​​​​​​

I just follow the instructions when you create the custom domain; works for everything else - tried that too (connect-production-ba24.up.railway.app) didn't work either - see screenshot. The incorrect error you see below is from a previous try to set the custom domain. You can also see in the other screenshot that it says setup complete and that's pointing to 007tej75.up.railway.app - done the exact same process for a couple of other deploys; and they work - but for some reason this one doens't.

I think it's a routing issue on Railway’s end and need staff to check the proxy config.​​​​​​​​​​​​​​​​

Nothing wrong on our end, this would be a misconfiguration, so I'll let the community help you with it!

Could you solve this? 🙂

same issue

https://station.railway.com/questions/custom-domain-returns-502-404-while-defa-27722827

thanks for the detailed report!

Since your Railway URL (connect-production-ba24.up.railway.app) returns a healthy response but your custom domain (connect.gainable.dev) returns a 502, the issue is almost certainly in the proxy/routing layer between your custom domain and your service — not in your app itself.

A few things to check and try:

1. Verify the CNAME target matches your service

You mentioned the CNAME points to 007tej75.up.railway.app — make sure this is the target Railway assigned specifically for your custom domain, not a different service's target. You can confirm this in your service's Settings → Custom Domains section.

2. Check for multiple services in the project

If you have more than one service in this project, ensure the custom domain is attached to the correct service (the one running on port 3000). A 502 "Application failed to respond" can occur when the domain is routed to a service that isn't listening on the expected port.

3. Confirm the PORT environment variable

Make sure your app binds to 0.0.0.0:3000 (not 127.0.0.1:3000 or localhost:3000). While this typically causes issues on the Railway URL too, it's worth double-checking.

4. Remove and re-add with a fresh DNS flush

Try this sequence:

Remove the custom domain from Railway

Delete the CNAME record from your DNS provider

Wait a few minutes for propagation

Re-add the custom domain in Railway and set up the new CNAME target provided

5. Check for a CDN or proxy in front

If you're using Cloudflare or another proxy/CDN in front of your DNS, try setting the DNS record to DNS only (grey cloud in Cloudflare) rather than proxied. Proxied mode can interfere with Railway's TLS termination and routing.

If none of the above resolves it, sharing the request IDs you provided (V8Rk1rl0QNaV-9k0jUJq2g, 7V0kP10BTsmsvHclw9P4nw) with Railway support directly would help them trace the routing path on their end.