Is there any possible way to decrease the spawn rate for mobs on Aternos?

Me and my friend are using a server and every time it becomes nighttime, way more mobs than normal start spawning, we had atleast 20 zombies on us the first night and 5 spiders, it gets very annoying and we usually stay indoors, but it would help if anyone knows how to fix this, we are on Version 1.15.2 and have no Plugins or anything enabled.