My computer is connected via Cat5 direct to the router while my ipad is wireless. Both have the same issues.
The ipad's Safari browser clears it's cache each time that Safari is closed and it cannot use plugins or third-party add-ons.
As far as my FireFox goes, the only third-party add-on is Flashgot, otherwise it's fully updated, currently v.47.0
And to reply to this thread, I had to close my ipad and come in with my computer, since the Safari was not "seeing" the "Post Reply" text area, but Firefox did. (and here I am)
Earlier, though, my computer did not see the "Post Reply" text area but the ipad did.
There doesn't seem to be a set pattern to this - it can work fine all day, then all of a sudden, one or the other won't see certain parts of the forum or be able to use the features.
I honestly suspect that it's a database issue.