Constant webrtc_unreliable::MAX_MESSAGE_LEN

pub const MAX_MESSAGE_LEN: usize = MAX_SCTP_PACKET_SIZE - SCTP_MESSAGE_OVERHEAD; // 16_356usize

Maximum supported theoretical size of a single WebRTC message, based on DTLS and SCTP packet size limits.

WebRTC makes no attempt at packet fragmentation and re-assembly or to support fragmented received messages, all sent and received unreliable messages must fit into a single SCTP packet. As such, this maximum size is almost certainly too large for browsers to actually support. Start with a much lower MTU (around 1200) and test it.