Have you tried this to fix the config page?:
Bitmain released a new firmware for the S3+ that now includes version 4.6.1 of cgminer. Unfortunately the firmware, at the time of writing this, contains an error which makes it impossible to update the miner configuration. There is a fix for this:
1. Download and flash firmware from:
https://bitmaintech.com/support.htm?pid=007201407180243004432lBQW28O06332. When the rig reboots, SSH into the S3 and login (remember if you chose not to keep settings while flashing, it will pop up on the default IP of 192.168.1.99 rather than its previous IP).
3. Enter this and press enter: sed -i 's/Save\&Apply/Save\&Apply/g' /usr/lib/lua/luci/model/cbi/cgminer/cgminer.lua
glws