We noticed that some users complaint about iPhone’s connection. (iPhone can not be connected to POP)
Several users solved the problem after trying the below method from @Robr57
You can try to use this method to revise the POP’s name and password firstly.
Here is the download link of Windows Handy Scan: https://revopoint3d.com/wp-content/uploads/download/HandyScan_Setup2.4.8_20210513.R.exe