Minecraft Forge server crashes PCs connection

[HardStroke]

Hey

I have a server that I'm playing with my friends on and we are facing a problem

we have about 109 mods loaded

we have a big Refined Storage system and if we try to craft iron blocks for example and shift click them to craft a stack, it crashes my computer's internet connection, not the whole internet

its also happening when we come back to the overworld from the twilight forest

its lags for 5-10 seconds and my computer's internet connection dies

I have a pretty solid internet connection with fiber optic cables, 500MB/s download and 50MB/s upload

its not the cable because the cable is new and is made for those internet speeds and even greater so I do get the whole bandwidth 

server is on the latest 1.12.2 forge

important pc specs:

10600K (Overclocked to 4.9GHz-5GHz on all cores)

Z490 Vision G (latest LAN drivers)

32GB of ram (4 sticks of 8GB running at 3600MHz CL18-22-22-42)

exact model: CMK16GX4M2D3600C18

Server has 12GB of allocated ram to use, never went above 5-6GB

minecraft has about 32GB of allocated ram but it barely uses 6 and the game itself is running perfectly fine