Just to check my assumption, you are on a wired connection, not wireless, between computer and router/modem, yeah?
Assuming so… both good and bad news, the answer is almost certainly not. It isn’t impossible that this is the network card, but it almost certainly isn’t – not least because most of the time the onboard NIC is an Intel ethernet controller part of the chipset, and those are just fine.
To find out for sure, posting the log somewhere for people to see might help, but the best thing to do is measure to find out where the problem is. The best tool and guide I know that covers every step is https://www.pingplotter.com/fix-your-network (The free version is more than fine for this.)
If you point that at 8.8.8.8 (Google DNS) you have something with a known good server-side to test against; if you point it at an IP used while you are playing with friends that’ll show you the details of communication between you and them. Both have value, and sometimes 8.8.8.8 will show up the problem quickly.
Feel free to post screenshots if you need help understanding the results of PingPlotter.
Beyond that, word of advice: almost all the “TCP optimizer” things are either snake-oil, or actively counter-productive. They usually “solve” problems that don’t really exist, and can make things much, much worse by, eg, disabling features that make it possible for the OS to communicate effectively with other systems.
If you can undo whatever they did, probably a good idea.