Unable to connect a remote disk using afp
So you should know that AFP is deprecated as of 10.11 and SMB should always be used where possible.
The next OS X (10.12) will drop AFP support entirely.

Besides that, Given that the log is suggesting the kernel extension for AFPFS is unable to load due to missing dependencies you may want to look at either reinstalling the 10.11.5 Combo Update or reinstalling the whole OS over the top.

Combo Update can be grabbed here:
https://support.apple.com/kb/DL1876?viewlocale=en_AU&amp;locale=en_AU

For the reinstall, make sure you have a known good backup with time machine or similar.
https://support.apple.com/en-au/HT201250

Re-Install El Capitan by going to the App Store, search for it, download it and install once completed. It will install 10.11.5.