fix: update sendPing to prevent HMAC-MD5 verification hash from being added for null UUID connection

src/OverteClient.cpp

@@ -1552,10 +1552,10 @@ void OverteClient::sendPing(int fd, const sockaddr_storage& addr, socklen_t addr
     // Ping type (0 = local, 1 = public)
     packet.writeUInt8(0);
     
-    // Add HMAC-MD5 verification hash using null UUID as connection secret
+    // NOTE: Do NOT add HMAC verification hash!
-    // (domain server uses null UUID for clients that haven't been assigned a connection secret)
+    // The domain server adds our node with a null UUID connection secret,
-    uint8_t nullUUID[16] = {0};  // All zeros = null UUID
+    // which means NO HMAC is set up for our node. If we send an HMAC hash,
-    packet.writeVerificationHash(nullUUID);
+    // the server expects an empty hash and rejects our packet.
     
     const auto& data = packet.getData();