Random lag spikes

Hello , I've been getting random lag spikes for some quite time when I play on xbox and pc. Recently I upgraded my service to gigablast. But it still does it , I've been doing speed test when theres no issues and when I get spikes. I get around 560mb download & 3mb upload on a good moment. 190mb - 300mb & 0.5mb upload when I get spiked.Also my router just loses internet at random times . I have a couple people connected on my router but they mostly watch videos or go on social media. Just mostly affects me whenever I play games. Don't know if I need things to be checked out or what.