Digi TransPort WR31 User Manual page 317

Configure network interfaces
Enable MPPE stateless mode
When this setting is enabled, the router negotiates stateless mode in which the session key is
changed after the transmission of each packet. Stateless mode may be useful for lossy links.
Note MPPE does not provide authentication, only encryption. This is because the encryption keys
are determined by the PPP engines themselves on start-up.
Use PPP m for processing CHAP
TCP transmit buffer size n bytes
When the value in this text box is set to a non-zero value, the router uses the value to set the size
of the TCP buffer for transmitted packets. This is useful for slow and/or lossy connections such
as satellite links. Setting this buffer to a low value will prevent the amount of unacknowledged
data from getting too high. If retransmits are required, a smaller transmit buffer helps prevent
retransmits flooding the connection.
Digi TransPort WR Routers User Guide
Configure Advanced interfaces settings: External modems and PPP
317