I host a small ATM 8 server using g-portal for 2 other friends, they're the only ones that know the IP, have the same pack version as the server, and i know they haven't given the IP to anyone else. I'm consistently getting a vanilla connection attempt refusal at ~20-40 minute intervals. Ive contacted g-portal, they've moved me to a new ip and i immediately received another one of the connection attempts.
Here is a screenshot of the last couple days of logs, searching for said log string.
https://i.imgur.com/OYcYqqq.png
Here is the full log string including the previous line.
[21Jul2023 18:06:44.464] [Netty Epoll Server IO #13/ERROR] [net.minecraftforge.network.NetworkRegistry/NETREGISTRY]: Channels [voidtotem:totem_effect_packet,structure_gel:main,blue_skies:main,sfm:disk,potionsmaster:main_channel,systeams:recipe_version_check,xycraft_core:main,corgilib:network,compactmachines:main,aiotbotania:netchannel,tempad:main_channel,laserio:main_network_channel,reliquary:channel,hexerei:channel,toolbelt:general,mythicbotany:netchannel,moonlight:channel,littlelogistics:tug_route_channel,pylons:main,charmofundying:main,rechiseled:main,littlelogistics:vehicle_tracker_channel,libx:netchannel,endertanks:main_channel,polymorph:main,advgenerators:generators,minecolonies:net-channel,tombstone:tombstone_channel,travelanchors:netchannel,artifacts:main,phosphophyllite:phosphophyllite/configsync,compactmachines:room_tracking,waystones:network,hexal:main,itemcollectors:main,sebastrnlib:sebastrnlib,sophisticatedbackpacks:channel,computercraft:network,constructionwand:main,energymeter:network,mekanism:mekanism,hexerei:network,configured:play,alchemistry:main,gravitationalmodulatingunittweaks:gravitationalmodulatingunittweaks,productivebees:buzzinga,quarryplus:main,blueflame:fire_channel,ad_astra:main,curios:main,rebornstorage:main_channel,trashslot:network,universalgrid:main_channel,sophisticatedcore:channel,multipiston:net-channel,twilightforest:channel,mininggadgets:main_network_channel,utilitix:netchannel,modularrouters:main_channel,structurecompass:main,cfm:network,silentlib:network,simplemagnets:main,modonomicon:main,immersiveengineering:main,morphtool:main,cosmeticarmorreworked:main,alchemylib:main,littlelogistics:locomotive_channel,morered:main,mahoutsukai:main_channel,byg:network,lootr:main_network_channel,nochatreports:main,merequester:network,occultism:main,dpanvil:main,spirit:main_channel,botania:main,wirelesschargers:main,shrink:main_channel,framedblocks:main,supermartijn642configlib:sync_configs,quark:main,silentgear:network,bdlib:misc,supplementaries:network,platforms:main_channel,engineersdecor:default_ch,crafting_on_a_stick:main,buildinggadgets:main,tetra:main,sfm:manager,farmingforblockheads:network,ad_astra_giselle_addon:main,forge:tier_sorting,integratednbt:main,naturesaura:network,harvestwithease:main,caelus:main,rsgauges:default_ch,dummmmmmy:network,sophisticatedstorage:channel,advancedperipherals:main_channel,theurgy:main,hexcasting:main,create:main,tesseract:main,bdlib:multiblock,createaddition:main,comforts:main,phosphophyllite:multiblock/guisync,cookingforblockheads:network,mekanismgenerators:mekanismgenerators,elementalcraft:main,securitycraft:securitycraft,solcarrot:main,structurize:net-channel,fluxnetworks:network,patchouli:main,pneumaticcraft:main_channel,trashcans:main,dimstorage:net,geckolib3:main,ars_elemental:main,elevatorid:main_channel,sfm:labelgun,shetiphiancore:main_channel,refinedstorage:main_channel] rejected vanilla connections

[21Jul2023 18:06:44.464] [Netty Epoll Server IO #13/INFO] [net.minecraftforge.server.ServerLifecycleHooks/SERVERHOOKS]: Disconnecting VANILLA connection attempt: This server has mods that require Forge to be installed on the client. Contact your server admin for more details.

From my testing ages ago, this was some sort of bot spam from some datacenter in Europe, just pinging the default MC port