The help for PPS is :
Password-protected sharing is on by default for computers in workgroups. When password-protected sharing is turned on, people using other computers on your network can't access your shared folders or printers unless they have a user account on your computer. There are two ways to turn on file or printer sharing:
Create identical user accounts on all computers in the workgroup (recommended). For more information, see Create a user account.
Turn off password-protected sharing. To turn off password-protected sharing, follow these steps:
Click to open Advanced sharing settings.
Click the chevron to expand the current network profile.
Under Password protected sharing, click Turn off password protected sharing, and then click Save changes. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
It does work when PPS is off on both? Not clear from your message? Also check the TCP/IP settings, like the NetBios helper, all are needed?
Have you tried re-booting the Router? Could be part of the problem?