main point is your hardware is likely to be ok, steam is likely to be ok, the fault is in the OEM network driver that did not get updated. over time network specifications change, how things are done change, new bugs are discovered and fixed. You just need the updates and OEM drivers make it hard to find the updates.
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what caused it is most likely that OEMs are jerks and will not provide updated drivers to microsoft so they can update your system with windows update. OEMs used to be charged 20k for microsoft to take their driver and test it and put it into windows update. (they don't charge now but OEMs still refuse to provide the drivers for various reasons)
the OEMs gives microsoft a stripped down driver so that windows can detect the hardware and get basic functionality.
You are then expected to go and get a proper update from them. Problem is most people never do and they just end up running on a very old OEM driver. Then they start using software that assumes that the network has no bugs and their software then has to deal with the bugs in the drivers. The net effect is that any software that depends on a network driver may fail. Streaming software, antivirus software and even GPU software (in the case of nvida with shadowplay enabled by default)
Sammyjo20 :
Thanks for the help. What do you reckon caused it? The downloading of the game or my hardware?