Hey, I encountered this issue in July, and I reported it as a bug here: https://bugzilla.kernel.org/show_bug.cgi?id=208637. See the bug report for logs. Here's the description: I have been trying to establish secure connection to a gatt service. Pairing completes successfully (using out-of-band data), and the client can read characteristic that has encrypt-authenticated security level, but the connection is lost soon after pairing (as seen in the btmon log). This seems to happen because the controller responds with reason Connection Timeout (0x08). Hardware: Raspberry Pi 4 Model B (Bluetooth chip: Cypress CYW43455). Tested on: 4.19.118-v7l+, 5.4.42-v7l. Tested BlueZ: 5.53, 5.54, master (commit 6ea1b038eedeca31c3796ac921e25509d48d70ec) Best regards, Jari Jääskelä
