Correction: further fiddling reveals I can’t change the limit to 0 for no limit.
I can change it to 10,000 and the speed to 600 for example and it stays. But if I try setting the limit to 0… poof! resets both fields to the default.
SO, I’m good with that, but might be a clue for you folks.
I talked to our upline and they gave me an .htaccess line to add
AddHandler application/x-httpd-php53 .php
This fixes the server error when attempting to set the Sending Speed And Limits, however the settings immediately revert to the defaults instead of actually changing.
Ah! Merci. That was it. My ftp client’s upload options windows were hidden and those files did not get uploaded. All good now 🙂