You might have issue with people picker in InfoPath form on Sharepoint online site. I would like share an update with you on this issue.
Symptom: You get error "Unknown network error" while resolving the user in people picker control in InfoPath filler form at your SharePoint online site.
Note: The people picker is working as expected in browser based form.
We were able to identify the offending code change and the problematic deployed code has been disabled now.
Published by: Neelesh Rai