There are a lot of issues with this guide you should probably double check it.
Don't quote my entire guide please, delete your post. Feel free to post the abundant issues though.
Most of this is a copy paste of the S3 guide, where do I start....there is so many things wrong with it. You even posted "Using a browser, navigate to 192.168.1.99 - this goes to the S3's configuration page.", half of the things under the troubleshooting section are wrong as well.
Maybe because two miners using exactly the same architecture will have a very similar setup? So far you've found one character wrong, anything else? Still not sure why you're coming into this so aggressively... would you rather there be no resource at all or would you rather make your own thread?
Actually the S4 is is many ways much more similar to the S2 because of the beagleboard. Guess ill list off some stuff since you don't even see it. I have more a problem with there being wrong information than merely incomplete information. I see you fixed SSH username/password one but there are still others.
Problems:
Bitmain firmware updates are no longer released on their github, they are now on the bitmaintech.com support section, the github was last updated on April 13th as you can see.
Upgrading the firmware can help with x's over chips as well, x's don't necessarily mean its dead on S4 due to issues with the first firmware release.
The difficulty issue affects pools that start on a diff of 1 and then slowly ramp up, if the pool starts on a diff of 1 and ramps up in a few seconds there is not an issue, variable difficulty itself is not the issue, ramping up from low difficulty is.
A single faulty chip should not affect it by ~3%, it should be under 1% since there are 160 chips on a S4.