That particular one, only TCP. There is a different one for UDP applications: https://www.rfc-editor.org/rfc/rfc8899 https://www.rfc-editor.org/rfc/rfc8899 Bec

That particular one, only TCP. There is a different one for UDP applications: https://www.rfc-editor.org/rfc/rfc8899 https://www.rfc-editor.org/rfc/rfc8899 Because UDP is only a very thin layer, each layer on top (eg, QUIC) has to implement PLPMTUD; although, recently IETF standardised a way to extend UDP to have options and PLPTMUD is also specified for that: https://datatracker.ietf.org/doc/draft-ietf-tsvwg-udp-options-dplpmtud/ https://datatracker.ietf.org/doc/draft-ietf-tsvwg-udp-option...