1. First of all, make sure you have the latest version of Microsoft Data Access Components (MDAC)installed.
2. Try to increase query timeout in the ‘Remote server connections’ property.
3. One more advice on how to resolve this issue in synchronizing tools is using the 'Quantization' option . As the chances of errors occurring is higher in large tables, apply this feature to a table that has the 'object was open' error.