Why is my Minecraft server sending so many packets?

Overview

We've been playing together with friends on a server I host for a week or so now, since I'm running the server 24-0 people started noticing that whenever I connect to it, they'll instantly start noticing very bad connection problems, however I wasn't experiencing that, since I'm connected locally. The moment I disconnect, the issue stops, and everyone goes back to having good connection. This made me curious to why this happens, so I started monitoring the network traffic of the server PC and turns out they're correct.

The server when I'm not on:

The server when I'm on:

I just couldn't find why this is happening. I got Wireshark and started monitoring what really happens. It's basically a billion packets with [ACK] and [PSH,ACK] tags, using TCP (the data itself is encrypted).

The worst part is, that I increase everyone else's internet use with this, because clients communicate between each other too, so the images you see there, the big network spike happens to all my friends too, when I'm on the server. It's like my Minecraft wants to DDOS everyone.

So I assume two things.:

1. There's a network loop somewhere and I don't know where or how could I find that.
2. Since I'm connecting locally, the server detects low latency and thinks it's ok to update everything about my connection every nanosecond, and just floods the router with packets, choking everyone else out.

I couldn't find any solution to that, not even this happening to anyone else, so I'm turning to this forum. If you have any idea why this could be happening, please help.

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Specifications

The server is running on a completely different PC on my local network and is connected to the same router as my client PC. The server has a static IP address.

• Server: FTB direwolf20 modpack(v 1.10.1)
  • RAM: 24GB (18 utilized)
  • Processor: Intel i5 6600
• Internet Connection
  • Download Speed: 500mbps
  • Upload Speed: 20mbps
• Minecraft Version: 1.16.5