Internet (router) problem

My router broke down, Rostelecom arrived, installed a new one, the Internet connection is good, I download and upload everything quickly. But when I want to upload something, photos, or videos, or just put a new avatar on Vkontakte, then I don’t give all the best, and if I do, then for hours, there were no such problems with the old router. I also cannot play gta online normally (it does not save the process). The Avast Secureline VPN program helped me, when using it, everything works fine, but it is paid and is given only for 7 days. But with Wi-FI, by the way, everything is fine too, that is, I can calmly upload everything from my phone. So how can I fix this problem, can I change something in the settings of the router?