Modbus Data via a Serial Bridge (TS4 Portserver) is altered, is there an alternate configuration?

The application is on a TS4 MEI, setup as follows:
Realport drivers on PC for legacy polling application to use virtual comm port to poll modbus RTU device on Port 1.
Port 1 - Realport, RS485 modbus slave device (9600 8N1)
Port 2 - RS232 (9600 8N1), serial bridge to port 1 for local laptop access to port 1 RS485 device, same polling application used as the legacy PC using realport.
All applications on legacy PC using realport are shutdown when using local port 2.

The data is good when polling from legacy app on PC using realport, 10%-20% the data points are changed when polling with the same application on port 2 using the local laptop. The laptop application does not report any communication errors, just altered data. When the digi is bypassed and a simple 232-485 converter is used with the laptop, the data is intact and not altered.

Are there CLI parameters on the digi to tune the serial bridge for modbus?
Is there an alternate configuration for this setup?