Haven't learned enough to get communications logs from the server yet, but here's what pronterface sees:
<blockquote class="Quote">Connecting...SENT: M105RECV: ok T:25.0 /0.0 @0 B:25.5 /0.0 @0Printer is now online.>>> M115SENT: M115RECV: FIRMWARE_NAME:Smoothieware, FIRMWARE_URL:http%3A//smoothieware.org, X-SOURCE_CODE_URL:https://github.com/Smoothieware/Smoothieware, FIRMWARE_VERSION:edge-6a3b837, X-FIRMWARE_BUILD_DATE:Aug 28 2020 22:01:51, X-SYSTEM_CLOCK:120MHz, X-AXES:5, X-GRBL_MODE:0, X-CNC:0, X-MSD:1RECV: ok