The file you have provided is a backup, which is missing important device logfiles for further analysis. Thus, I would like you to attach another, a troubleshoot file to your question. Please, replicate the issue, then access router's WebUI, go to System -> Administration -> Troubleshoot section and download troubleshoot file from there.
From what is provided, I can suggest to update router's firmware to the latest with Keep settings option disabled. Please download file from here. Be aware, that updating without Keep settings, will erase your current configuration, but will help to avoid any migration issues due to several iteration difference between versions.