we have server farm with SharePoint and Project Server 2013
and we havent any problem in last year but today cant connect any client Microsoft Project 2013 Professional to server PWA
/_vti_bin/PSI/WssInterop.asmx?wsdl
psi available and firewall off
but MSP Microsoft Project client cant connect to server and fire this error for me
after config Search server in one added new server in farm this errors accured
1-one way to reoubleshooting is : Set-SPProjectPermissionMode
project server permission mode
2-Additional Server Settings page, in the Project Professional Versions section, type the build number of each Project Professional version that you want to connect to Project Server 2013. Use a comma as a separator between multiple version numbers
3- permission level and groups like this: