diff --git a/src/pymc_core/protocol/constants.py b/src/pymc_core/protocol/constants.py
index d5b23d9..3859b87 100644
--- a/src/pymc_core/protocol/constants.py
+++ b/src/pymc_core/protocol/constants.py
@@ -45,16 +45,15 @@
 # ---------------------------------------------------------------------------
 # Misc sizes
 # ---------------------------------------------------------------------------
-MAX_ADVERT_DATA_SIZE = 96
+MAX_ADVERT_DATA_SIZE = 32
 PUB_KEY_SIZE = 32
 SIGNATURE_SIZE = 64
 PATH_HASH_SIZE = 1
 CIPHER_MAC_SIZE = 32  # SHA‑256 HMAC
 CIPHER_BLOCK_SIZE = 16
-MAX_PACKET_PAYLOAD = 256  # firmware's default
+MAX_PACKET_PAYLOAD = 184  # firmware's default
 
 MAX_PATH_SIZE = 64
-MAX_PACKET_PAYLOAD = 256
 MAX_HASH_SIZE = 32  # SHA-256 truncated
 
 NAME_MAX_LEN = 16  # Max length of a contact name