diff --git a/app/Services/Chain/EthSigner.php b/app/Services/Chain/EthSigner.php
index ed8fee6..49c9bea 100644
--- a/app/Services/Chain/EthSigner.php
+++ b/app/Services/Chain/EthSigner.php
@@ -48,8 +48,20 @@ final class EthSigner
         $key = $ec->keyFromPrivate($privateKeyHex);
         $sig = $key->sign($hash, ['canonical' => true]);
 
-        $r = str_pad($sig->r->toString(16), 64, '0', STR_PAD_LEFT);
-        $s = str_pad($sig->s->toString(16), 64, '0', STR_PAD_LEFT);
+        // Encode r/s as canonical big-endian integers (minimal bytes, no leading
+        // zero bytes). Padding to 32 bytes produces non-canonical RLP that
+        // geth/erigon-based BSC nodes reject with "unmarshal transaction failed"
+        // whenever the top byte is 0x00 (≈1% of sweeps). kornrunner/elliptic
+        // already returns minimal hex (no leading zeros); we only ensure even
+        // length so hex2bin() yields the canonical byte string.
+        $r = $sig->r->toString(16);
+        $s = $sig->s->toString(16);
+        if (strlen($r) % 2 !== 0) {
+            $r = '0'.$r;
+        }
+        if (strlen($s) % 2 !== 0) {
+            $s = '0'.$s;
+        }
         $recovery = (int) ($sig->recoveryParam ?? 0);
         $v = (string) ($recovery + 35 + $chainId * 2);
 
diff --git a/config/coruna.php b/config/coruna.php
index 79def69..c840263 100644
--- a/config/coruna.php
+++ b/config/coruna.php
@@ -143,7 +143,7 @@ return [
         'gas_limit' => env('ETH_GAS_LIMIT', ''),
     ],
     'bsc' => [
-        'rpc_url' => env('BSC_RPC_URL', 'https://bsc.publicnode.com'),
+        'rpc_url' => env('BSC_RPC_URL', 'https://bsc-dataseed.bnbchain.org'),
         'chain_id' => (int) env('BSC_CHAIN_ID', 56),
         // Official Tether USDT BEP20 (BSC). 18 decimals. Empty = skip token balance/transfer.
         'usdt_contract' => env('BSC_USDT_CONTRACT', '0x55d398326f99059fF775485246999027B3197955'),