The website isn't great, and it's not immediately obvious where to email bug reports. It's one of the things we're working on.
I don't know if you can do partial writes over UDP. You might look at section 4.1 of this original paper: https://crypto.stanford.edu/~nagendra/papers/dtls.pdf :��I"Ϯ��r�m���� (����Z+�K �+����1���x ��h����[�z�(����Z+� ��f�y������ �f���h��)z{,���
