To me it's very clear you're suffering from a packet issue. All of the above recommended solutions, apart from updating drivers, are useless and are not going to fix your issue. While the above replies are ofcourse ment in good faith, changing your DNS or disabling controller input for garry's mod are very silly suggestions...
What is happening is that for a short duration you are not receiving any incoming packets, while you are sending them(see the in and out on your net_graph. There can be many reasons why you're losing packets. Some can even be out of your control.
It appears you're on Wi-Fi. Wi-Fi is
inherently unreliable. Your current issue can be explained by a neighbour turning on his microwave, a guy firing up his Drone 5 miles away or a satalite transmitting data. That's besides the dozens of devices in your home sending a signal every second that they still exist while your computer is scanning all of those signals every minute or so. Wi-Fi by design sucks ass for Time-sensitive applications.
I don't know your setup but if you're on Wi-Fi and using any OEM onboard hardware you are fucked. Even if this only just recently started occuring get a cable. you
can get a powerline adapter if you are unable to run a cable but they are also not without issues.
You could mitigate your current issues by disabling autoconfig on your Wi-Fi adapter.
It's going to happen again as soon as the cause returns.