Are you only getting IO Timeout during disconnection periods (2 IO timeout values per disconnection) or is it never able to collect data for those digital tags?
If it never collects data, then you may want to look in the message logs for any errors for those tags. Also, make sure that the digital set from the source server also exists on the target server.
Additionally, you should set up debugging for at least a couple of tags by setting location3 appropriately (as long as location3 override (/C3) is not defined in the interface configuration).
Please report back with the error messages you are seeing.