Ionic Download error on certain connections


I have an Ionic iPad app that uses Native File and File transfer to download assets to the device.

My client is in Dubai and every now and then he gets a conn_err message when trying to download. It never happens here (Africa).

He has tried different internet connections, and this happens intermittently.

My question is, could a corporate network, VPN or internet restriction in Dubai possibly effect the download process of these files?

They are coming from a secure remote server.

I cannot debug this. The only thing i can see is conn_err but he says his internet is stable.

Any help would be appreciated

Kind regards