I was wondering if the usual TCP window setting of 840 makes any sense in our current mesh.

This setting was imposed by the assumption that our IP traffic will pass over ax.25 connections, with their MTU and ACK limitations, and does not affect AXIP, AXUDP or other transfer modes.

I am using -w 0 to override this handling. Note that it does not work in the scenario you depict: the setting only has influence on an end-system (where tcp connections terminate), not on a forwarding gateway. Only when a gateway is an end-system as well, this setting has any effect. And in that case it is not likely it is operating over ax.25.

I think it is the responsibility of end-systems on a slow ax.25 network to configure a proper window size. The gateway does not have a role in that.

Rob