We are getting a 504 Gateway Timeout when trying to preview a form with a large amount of heavily populated dropdown lists. There are 15 dropdowns, each with around 1000 options (these are affiliations that can be selected by individuals). I can view and manipulate the form in "Design" fine, it just fails to load once I go to test it. Any advice?
I think you are reaching limits of how many fields/options we can support on test/html side. There are different code implementation between "Design" and "Fillable Form/Test" sides, where the "Design" side is more optimized to handle large number of elements, while on the "Fillable" side we are more restricted in what we can support.
The only advice I currenlty have is to try to split the form into several ones and reduce the number of options per field. Not sure if its applicable in your case, but maybe divide affiliations into different groups/regions and use separate form for each group. This way it also can be easier on form fillers (trying to select an option out of 1000 dropdown elements can be somewhat difficult)
We'll also look to see what optimization we can do to better handle such large number of options on the fillable side.