InfoPath cannot connect to the server.

Symptoms:
“InfoPath cannot connect to the server. The server may be offline, your computer might not be connected to the network, or InfoPath Forms Services 2010 might not be enabled on the server. To fix this problem, start by checking your network connection, and then trying again.”
 Following feature is also enabled in the site collection
 SharePoint Server Enterprise Site Collection features
Features such as InfoPath Forms Services, Visio Services, Access Services, and Excel Services Application, included in the SharePoint Server Enterprise License.

Solution:

This issue may be caused by InfoPathFormsServices. To fix this, reactivate the "IPFSSiteFeatures" feature (hidden feature) at site collection level.

You can run below PoweShell Command to Disable and re-enable the "IPFSSiteFeatures" for the site collection having issue.

C:\> Disable-SPFeature "IPFSSiteFeatures" -url "http://Server/Sites/SiteCollection"
PS C:\> Enable-SPFeature "IPFSSiteFeatures" -url "http://Server/Sites/SiteCollection"

 

Another Solution:

You can run the following stsadm command at site collection level to deactivated and reactivated InfoPath Forms Services on your SharePoint site:

 

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>STSADM.EXE -o deactivatefeature -filename IPFSSiteFeatures\feature.xml -url http://servername/site/sitename -force 

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>STSADM.EXE -o deactivatefeature -filename IPFSWebFeatures\feature.xml -url http://servername/site/sitename -force

 

To reactivate IPFS:

 

 C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>STSADM.EXE -o activatefeature -filename IPFSSiteFeatures\feature.xml –url http://servername/site/sitename -force

 C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\BIN>STSADM.EXE -o activatefeature -filename IPFSWebFeatures\feature.xml -url h http://servername/site/sitename -force