UPDATE: It's been a few days now and everything is still working. No problem connecting to one PC from the other now, so editing the HOSTS file appears to have solved the issue. Not sure what changed on both systems that now required me to do that, never had to do that before and I've had my PCs networked for years since XP without any problems.

For others having this same problem I'll sum up what worked:
  1. Open Windows Hosts file (for me, located in %WinDir%\System32\drivers\etc\hosts) in Notepad.
  2. On a blank line add the IP address of the PC you want to connect to followed by a space and then the PC name i.e. 192.168.1.101 OFFICEPC
  3. Save the Hosts file.


It should work without having to reboot.

Thanks to those who took the time to advise me. I appreciate it!