OTF Mattermost Can't Connect

## Description Mattermost client (desktop/browser) showed "couldn't connect to this server" when accessing `comms.optimifed.com`. The server was online in Railway and the default Railway URL worked fine. ## Steps to Reproduce The `optimifed.com` domain was moved to a new Cloudflare account. This caused: 1. **Stale DNS records** — Cloudflare auto-imported A/AAAA records from the old account's proxy IPs (104.21.59.155, 172.67.179.219). These were circular (Cloudflare pointing to old Cloudflare edge) and not real origin records. 2. **Wrong port** — Railway auto-detected port 8443 (Mattermost's TLS port). Since Railway terminates TLS, the correct internal port is 8065. 3. **Domain verification** — Railway couldn't verify the custom domain because Cloudflare's proxy (orange cloud) hid the CNAME target. ## Resolution 1. Deleted all stale A and AAAA records from the new Cloudflare account 2. Changed Railway port from 8443 to 8065 3. Set Cloudflare SSL/TLS mode to Full (Strict) 4. Temporarily set CNAME to DNS-only (grey cloud) for Railway domain verification 5. Once verified, flipped back to Proxied Service restored on 2026-03-24. ## Related - Tech asset: [[otf-mattermost]] - Related issue: [[otf-n8n-cant-connect]]