I don't know how it works with Gel batts, but with chargers that have an AGM setting, it is often just a little below what the Flooded setting is. That may or may not be the spec voltage for the AGMs you have. AGMs specs are all over the map for charging voltages.
Perhaps Gels are all the same, don't know. My Tracer solar controller has settings for Gel, AGM, and Flooded at 14.2, 14.4, 14.6.
The OP's solar controller should also be set to Gel of course.
My Vector portable charger also has settings for Gel, AGM, and Flooded. I don't know what the voltage is for Gel on that. AGM is lower than for Flooded. I have AGMs that specify charging voltage at 14.5-14.9 at 80F, which goes higher at lower temps. Not all chargers have temperature compensation. So 14.4 is too low for them, but would be ok for Lifelines, which have lower charging voltages
