There's a quick fix to get the advanced page working.
Issue is that querying the hardware takes often longer than the timeout is.

SSH into your miner (user pi or root) and edit file
in line 172 you can find the timeout for the fetch-values cmd
further in line 331, 339 and 347 is the timer controlling after what timespan the next query will be issued.

Do not reload. If two queries are issued to fast, there will be a timeout.
If you want to reload the advanced page (for ex. to load new modifications of advanced.html), switch to another tab like 'mining' wait as long as your timer is set in file advanced_settings.html before switching back.

Fine tuning works without web-interface as well, just edit file
and restart

If you want to know which dies cause trouble, watch file

connect to the screen session running bfgminer (user pi required)

Most cubes run stable below 300MHz. To get above this value you need to compile stuff on your own, but save your time: lot of errors causing many restarts, more energy consumption, and it's hashing slower.

LCD display text can be modified, too, if you like