PPP Over BLE - LCP Configure-Ack Not Acknowledged by Device

I'm implementing a PPP connection over BLE with a Sauermann gas analyzer using React Native. The device sends an LCP Configure-Request, but after I respond with a Configure-Ack (0x02), the device keeps resending the request instead of proceeding with the next step.

LCP Negotiation Flow (Expected) The device uses escaping (0x7D + XOR 0x20).

LCP negotiation steps:

1. Device sends Configure-Request (0x01).
2. App responds with Configure-Ack (0x02).
3. App sends its Configure-Request.
4. Device responds with Configure-Ack. In my case, step 2 seems to be failing because the device keeps repeating step 1 (sending Configure-Request).

What I’m Doing

Decoding and Modifying the Configure-Ack

• I decode the received PPP frame
• Modify the identifier byte to 0x02 (Configure-Ack)
• Recalculate the FCS checksum

const sendLCPConfigureAck = async (connection, receivedPacketEncoded) => {
    try {
        console.log("