If this error occurs when transferring data from PlayStation®4 to PlayStation®5, please try the following steps:
If your PS4 and PS5 are connected to the network wirelessly, try transferring data by connecting each console to the network using a wired connection or by connecting both consoles directly with an Ethernet cable.
Turn off your router and wait at least 5 minutes, then restart it.
Try transferring data again by going to Setting > System > System Software > Data Transfer
If you only want to transfer save data, please try transferring via another storage medium, such as online storage or a USB storage device as an alternative method.
Please note the following:
Do not use the Network Test feature while Background Data Transfer is in progress.
Do not manually turn PS5 into Rest Mode while Background Data Transfer is in progress.