No mobs spawn on Aternos servers. What to do?

I have an Aternos server with 30 mods in the 1.12.2. Unfortunately, no single mob spawns by itself (that is, only spawneggs and spawners spawn mobs).

Here are the mods listed:

ChickenASM-1.12-1.0.2.7

AirSupport-0.3.0

Block Armor 1.12.2-2.4.11

ColossalChests-1.12.2-1.7.0

CreativeCore_v1.9.39_mc1.12.2

CustomNPCs_1.12.2 (30Jan19)

CyclopsCore-1.12.2-1.0.4

Deco Craft 2.6.2_1.12.2

InventoryTweaks-1.64 + dev.146

OnlinePicFrame_v1.4.23_mc1.12.2

Open Blocks 1.12.2-1.8

OpenModsLib-1.12.2-0.12.1

PTRLib-1.0.3

PortalGun-1.12.2-7.0.2

Rex's-Additional-Structures-1.12.x- (v.2.2.1)

[1.12.2] SecurityCraft v1.8.11

architecture craft-1.12-3.80

chiselsandbits-14:30

iChunUtil-1.12.2-7.1.4

inventorypets-1.12-1.5.3.1

jei_1.12.2-4.14.4.264

magic clover-1.12-0.7.8

secretroomsmod-1.12.2-5.6.4

There was also the "Deadly Monsters Mod" on this server.

This mod spawns very many enemy mobs. That worked too. But no Vanilla Minecraft mobs were spawned (except Spawner or Spawnegg).

I have completely removed them (under mods and config)

Since she's gone, not a single mob spawns (not even peaceful ones).

PS: I do not know anything about such a thing. It would be nice if you write answers that everyone understands.

Enter in the chat / Gamerule domobspawning True

then it should work again

if not tell me!

I have already tried it twice.

Unfortunately not a single mob spawns (of course without Spawner or Spawnegg)

The problem has been resolved.

In the config of AirSupport you can set whether Vanilla Minecraft mobs are allowed to spawn or whether they can only "copy" them.