Cannot connect to custom node on port 18089 - connection error 400

[Paul1804]

Monerujo version: 4.1.7 'Exolix' (installed from F-Droid)
Android version: 12 (12 SKQ1.211019.001)
Device: POCO X3 NFC (MIUI Global 14.0.2 Stable)

Issue:
Monerujo cannot connect to my self-hosted Monero node, while Cake Wallet connects successfully with identical settings.

Node configuration:

• Domain: monero.magnoliya.homes
• Port: 18089 (SSL enabled)
• Setup: monerod (restricted-rpc) → SSH tunnel → nginx reverse proxy
• Certificate: Valid Let's Encrypt SSL certificate

What works:
✅ Cake Wallet connects successfully to monero.magnoliya.homes:18089
✅ curl with User-Agent "Monerujo/1.0" returns 200 OK:

curl -X POST https://monero.magnoliya.homes:18089/json_rpc \
  -H 'User-Agent: Monerujo/1.0' \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":"0","method":"get_info"}' -k

# Result: HTTP 200 with valid blockchain data

✅ monerod works in restricted-rpc mode:

curl -X POST http://localhost:18089/json_rpc \
  -d '{"jsonrpc":"2.0","id":"0","method":"get_info"}' \
  -H 'Content-Type: application/json'

# Result: HTTP 200 with valid data

What doesn't work:
❌ Monerujo returns "ОШИБКА СОЕДИНЕНИЯ 400" (CONNECTION ERROR 400) when testing the node

Server logs show:

146.59.10.99 - - [10/Dec/2025:15:26:40 -0500] "POST /json_rpc HTTP/1.1" 400 255 "-" "Monerujo/1.0"
146.59.10.99 - - [10/Dec/2025:15:26:42 -0500] "POST /json_rpc HTTP/1.1" 400 255 "-" "Monerujo/1.0"

tcpdump capture shows Monerujo sends:

POST /json_rpc HTTP/1.1
Host: monero.magnoliya.homes:18089
User-Agent: Monerujo/1.0
Content-Length: 56
Accept: application/json
Accept-Encoding: gzip
Content-Type: application/json; charset=utf-8

{"jsonrpc":"2.0","id":"0","method":"getlastblockheader"}

Interesting observations:

• Method getlastblockheader (no underscores) works when called directly via curl
• Method get_last_block_header (with underscores) also works
• monerod accepts both method name variants
• Some requests from Monerujo return 200, but the node test still fails

Questions:

1. Does Monerujo require any specific RPC methods for node validation?
2. Why does curl with the same User-Agent work, but the app doesn't?
3. Is there any documentation on Monerujo's node connection requirements?

Additional information:

• Port 18089 is specified in Monerujo settings, SSL is enabled
• No login/password specified (node runs in restricted-rpc mode without authentication)
• Certificate is valid and works in browser
• Cake Wallet connects to the same node without issues