First of all, here is the init-string: AT&B1&S1&H1&L1&W
If your cables/serial ports/whatever does not support hardware flow control, replace H1 with H2 and change your software configuration accordingly.
Remember that all serial communication between PC compatibles at rates above 19200 baud require UART 16550A chips, the 16450 has a smaaler FIFO buffer and will overrun.
Client DIP settings: 1001000000 (1 = On/Down, 0 = Off/Up)
Server DIP settings: 1001100000 (1 = On/Down, 0 = Off/Up)
To change init-strings you need to power off, set switch 8 ON, power on, type the AT commands as necessary, then turn the modem off, reset switch 8 to OFF and power back on.