The simple answer is, unless there's a problem with your firmware, there's no need to set the work diff on the web site.
Setting it on the web site will only take effect if you set it above the pool's calculated value.
If there is a problem with the firmware then avoid using a power of 2 like 2048 - instead use a little higher e.g. 2052
As usual, remember that the work difficulty has no effect on your reward other than variance.
Higher diff means higher variance, but not much of an effect unless you make it a lot high e.g. if you set it 10x higher.
kano's right 9as always), I did several tests with setting diff on the website, and finally and stopped and I let the pool decide what's best

(s3+ and S5's)