connection break

So i have a new pc, and a new internet. I have my pc connected directly into the modem. I can connect to the internet well, but after some heavier loads my ethernet plug seems to "freeze"? It thinks its still connected to the router, but when i log into my router via my phone, it isnt connected...

So as i mentioned, i am not a network guy, like, at all. I'm good with building computers and messing around with the PC hardware side of things but not the network, a bit above basic level. Recently, i wanted to connect a second PC to my network so i can have a LAN party with my neighbours so...