Sonicwall logs flooded with: destination for 255.255.255. 255 is not allowed by access control

I recently deployed a Sonicwall TZ200 (fw version: SonicOS Enhanced 5.6.0.11-61o) and after setting up SSLVPN access, the logs were being flooded with the following message:

1		03/20/2013 13:13:55.416	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
2		03/20/2013 13:13:51.672	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
3		03/20/2013 13:13:50.896	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
4		03/20/2013 13:13:50.176	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
5		03/20/2013 13:13:46.752	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
6		03/20/2013 13:13:46.016	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control				
7		03/20/2013 13:13:45.464	Info	SSLVPN	destination for 255.255.255.255 is not allowed by access control

I found a few discussion threads pertaining to this issue on the Sonicwall forums and I tried some of the solutions offered but none of them worked. If you have an account on the forums, you can see these discussions here:

https://forum.sonicwall.com/showthread.php?t=25636&highlight=destination+255.255.255.255

https://forum.sonicwall.com/showthread.php?t=24107&highlight=destination+255.255.255.255

https://forum.sonicwall.com/showthread.php?t=27473&highlight=destination+255.255.255.255

Through trial and error, I noticed that the messages stopped appearing in the logs (not immediately after, I might add) after disabling “Communication Between Clients” under SSL VPN -> Client Settings, and adding “WAN RemoteAccess Networks” to the Access List for the SSLVPN Services group (on the VPN Access tab) under Users -> Local Groups. The messages returned upon reversing these changes. I also noticed that whenever I enabled/disabled “Communication Between Clients”, the following error message was logged:

Adding L2TP IP pool Address object Failed.

I’m not sure if they’re related but they appeared to coincide. This doesn’t seem like the best remedy but at the time I wasn’t able to update the firmware on this device, so this was the next best thing. I’ll update this post once when I get a chance to update the firmware.