I've known this method for a while, but I haven't seen it used in reference to Rocket League yet, which is odd because of game's inability to handle even minimal latency variation which can make it extremely difficult to play. First and foremost, as everyone else says if you can play wired that is 100% the best solution, but it isn't 2010 any more, wireless technology has come an extremely long way, and not being able to play on a wired connection isn't the same burden it was even just a few years ago. I personally play on Wi-Fi and am fine on every single game aside from Rocket League. I did a bunch of testing of a bunch of different methods I found online and this was the only one that truly solved my issue.
Rocket League suffers massively from even small changes in ping. Even if you have excellent ping (<30ms) you can still find yourself lagging around while on WiFi because your ping is changing from 20ms to 25ms to 15ms to 18ms etc. etc. which changes the server's response times and causes an extremely degraded experience. For a lot of games this isn't a huge deal, or the games have ways to mitigate the effects. Rocket League however is a game that requires extremely fluid gameplay and players needs constant updates about ball and opponent locations in order to succeed. Often times on WiFi, players will experience a warning concerning "Latency Variation" which is the game warning you that your latency is changing rapidly and you need to prepare for a degraded experience.
This problem is actually very likely related to your network card, and not the game nor your distance to the server (that will impact your latency, but not the variation of it). Go ahead and open command prompt as administrator
and type the following:
You should get a response that is a few lines long that shows some information about your wireless seettings. One of the lines should say something like this:
Auto configuration logic is enabled on interface "Wi-Fi"
Auto configuration logic is enabled on interface "Wireless Network Connection"
If it does, you can continue on, if it does not, this method will likely not work for you.
What we are about to do is disable your network cards ability to search for new wireless networks because searching for these networks causes sharp dips in latency that are the cause of your in-game issues. This will need to be re-enabled if your need to switch wireless networks for a different network. Please make sure to have some way to noting down how to undo this change for the future.
Go back to cmd and enter:
netsh wlan set autoconfig enabled=no interface="Wi-Fi"
netsh wlan set autoconfig enabled=no interface="Wireless Network Connection"
depending on whether your interface name was "Wi-Fi" or "Wireless Network Connection" on the previous step. You should get the response: Auto configuration has been disabled on interface "[whichever]". If you get this message, you're all set! Go into a game of RL and test out the new connection, hopefully your latency will be steady from here on out and you can get back to enjoying the game!
If in the future you need to re-enable the network search, just open cmd as admin and type:
netsh wlan set autoconfig enabled=yes interface="Wi-Fi"
netsh wlan set autoconfig enabled=yes interface="Wireless Network Connection"
and you should be back to having network search.
I hope this helps! I was able to get rid of 95% of my latency variation issues with this. I still get one or two every now and again but nothing like I used to. If you have any questions just drop a reply and I'll try to answer them.