Whenever I play Minecraft I'll have no lag problem (connection wise) so I'll play for a few hours or so with no problems. After a while I'll open Skype and get in a call, and after about 10 minutes the other person on the end of the Skype call will go silent, and Minecraft will freeze (connection wise if I'm on a Multiplayer server), after about 5 seconds I'll be disconnected from the Minecraft server saying "Java.io.IOException: An existing connection was forcibly closed by the remote host" and Skype won't end the call, it'll just pick up like nothing happened. There's no warning before this happens, like no ping spikes, just the simple disconnect. And it's only when I'm using Skype, so I'm feeling like Skype is crashing Minecraft, or since they both use Java my router is cutting off both of them or something. Any help is greatly appreciated.
It must be problem due to limit of your internet speed.
skype needs a lot of upload and download speed and same is with mineecraft.
Use skype mobile app. That is the simplest solution.
from OP's comment it is clear that on mobile the skype is not using 3G/4G data. instead it is connected to the same network through which minecraft is being played. So in this case one solution which comes to my mind is
This will significantly reduce the upload rates and hopefully prevent minecraft from being disconnected.