IONOS Setup
Configuring a Subdomain in IONOS
1. Access IONOS Domain Settings
- Log in to IONOS Control Panel
- Navigate to Domains & SSL
- Select lettre.ai
- Click Subdomains
2. Create New Subdomain
Click Create Subdomain and enter:
- Subdomain name:
myservice(for myservice.lettre.ai)
3. Configure Forwarding
After creation, click on the subdomain to configure:
| Setting | Value |
|---|---|
| Typ | Beliebige URL |
| Weiterleitungsziel | https://lettre.ngrok.dev/myservice/ |
| Weiterleitungsart | Frame-Weiterleitung |
| Seiten-Titel | My Service |
Important: Include the trailing / after the path!
4. SSL Certificate
IONOS automatically provides an SSL certificate for the subdomain. The “SSL-Zertifikat zugewiesen” indicator should appear.
5. Wait for Propagation
DNS changes may take a few minutes to propagate.
Complete Subdomain Registry
Copy these values directly to IONOS Frame-Weiterleitung configuration.
Core Services
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
ai-platform.lettre.ai |
https://lettre.ngrok.dev/platform/ |
AI Platform |
inqua.lettre.ai |
https://lettre.ngrok.dev/inqua/ |
INQUA Studio |
inqua-report.lettre.ai |
https://lettre.ngrok.dev/reports/ |
INQUA Reports |
Document & Viewer Services
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
ai-viewer.lettre.ai |
https://lettre.ngrok.dev/viewer/ |
AI Viewer |
ai-scholar.lettre.ai |
https://lettre.ngrok.dev/scholar/ |
AI Scholar |
PDAI Scientific Works
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
euler-opera.lettre.ai |
https://lettre.ngrok.dev/euler-opera/ |
Euler Opera |
kepler-gw.lettre.ai |
https://lettre.ngrok.dev/kepler-gw/ |
Kepler GW |
copernicus.lettre.ai |
https://lettre.ngrok.dev/copernicus/ |
Copernicus |
waefler.lettre.ai |
https://lettre.ngrok.dev/waefler/ |
Waefler-Hamidi |
diaries.lettre.ai |
https://lettre.ngrok.dev/diaries/ |
Astronomical Diaries |
Heritage & Archaeology
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
sundials.lettre.ai |
https://lettre.ngrok.dev/sundials/ |
Ancient Sundials |
karman.lettre.ai |
https://lettre.ngrok.dev/karman/ |
Kármán Archive |
Correspondence
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
korrespondenz.lettre.ai |
https://lettre.ngrok.dev/korrespondenz/ |
AI Korrespondenz |
Voice & Audio (cooltool.io)
| Subdomain | Weiterleitungsziel | Seiten-Titel |
|---|---|---|
ai-meeting.cooltool.io |
https://lettre.ngrok.dev/ai-meeting/ |
AI Meeting |
ancient-sundial.cooltool.io |
https://lettre.ngrok.dev/ancient-sundial/ |
Ancient Sundial |
Note: For cooltool.io subdomains, follow the same IONOS steps but select cooltool.io instead of lettre.ai in step 3.
Quick Reference (Copy-Paste Ready)
# lettre.ai subdomains
ai-platform.lettre.ai → https://lettre.ngrok.dev/platform/
inqua.lettre.ai → https://lettre.ngrok.dev/inqua/
inqua-report.lettre.ai → https://lettre.ngrok.dev/reports/
ai-viewer.lettre.ai → https://lettre.ngrok.dev/viewer/
ai-scholar.lettre.ai → https://lettre.ngrok.dev/scholar/
euler-opera.lettre.ai → https://lettre.ngrok.dev/euler-opera/
kepler-gw.lettre.ai → https://lettre.ngrok.dev/kepler-gw/
copernicus.lettre.ai → https://lettre.ngrok.dev/copernicus/
diaries.lettre.ai → https://lettre.ngrok.dev/diaries/
waefler.lettre.ai → https://lettre.ngrok.dev/waefler/
sundials.lettre.ai → https://lettre.ngrok.dev/sundials/
karman.lettre.ai → https://lettre.ngrok.dev/karman/
korrespondenz.lettre.ai → https://lettre.ngrok.dev/korrespondenz/
# cooltool.io subdomains
ai-meeting.cooltool.io → https://lettre.ngrok.dev/ai-meeting/
ancient-sundial.cooltool.io → https://lettre.ngrok.dev/ancient-sundial/Troubleshooting
Mixed Content Error
If you see “Mixed Content” errors in the browser console:
- The frame is loading HTTPS but the content uses HTTP
- Ensure the Weiterleitungsziel uses
https://lettre.ngrok.dev/...
Page Not Loading
- Check ngrok is running:
curl http://localhost:4040/api/tunnels - Check router is running:
curl http://localhost:5000/health - Check backend service:
curl http://localhost:[PORT]/
CSP Font Errors
If you see Content Security Policy font errors: - This is caused by IONOS’s frame wrapper - Avoid base64-embedded fonts in your content - Use external CDN fonts instead