Fungus or something on my potted outdoor mandevilla. Suggestions?

Hi, this is all about the problems these plants can encounter https://www.gardeningknowhow.com/ornamental/vines/mandevilla/mandevilla-disease-problems.htm

Disease

Mandevillas are susceptible to leaf spot infections that often start as a brown or yellow spot on a leaf. The spot grows or multiplies, causing the leaf to turn yellow, then brown as it dies. These infections can spread to other plants in your garden, so quick action is key to save your mandevilla and its neighbors. Prune off diseased leaves or stems and pick up any leaves that have fallen around the plant's base. Treating the plant with a fungicide that's safe to use with blooming plants can help, but the if the infection is bacterial, you might need to remove the entire plant before the infection can spread to others.

Insects

Mandevillas can develop yellow leaves if they're being attacked by pests, such as scales, mealybugs, red spider mites and whiteflies. These insects typically live on the undersides of the leaves. They eat holes in the leaves and secrete chemicals that can encourage fungal growth. Turning some leaves over to discover if bugs are the reason for the yellow leaves. If they are, use a mandevilla-safe pesticide or organic insecticidal soap to help eliminate the problem.

appears to be a insect infestationSpray the soil and the leaves with horticultral oil making sure the upper and under leaves are covered.If in a pot it would be best to re-pot in fresh soil