Thank you for writing us with regard to Codebook, although I’m sorry to hear about the issue you are seeing.
It can be very difficult to troubleshoot network issues due to the large number of variables involved, but there are definitely a few things we can try here. We’ve written up a short set of common troubleshooting instructions here:
Would you mind giving some of the suggestions in this document a try, and let us know what you find?
If none of these options work, it might be worthwhile to use Dropbox or Google Drive to sync your data, as it bypasses many of the common issues with WIFI synchronization. Here is a brief document that explains how to sync via alternate methods.