Join game lobby with serious delay (Client)

I've looked everywhere on the internet and the people who have this issue never find a solution and are never addressed. Whenever i play normals with my friends or by myself, i'm always the last person to join - even though i don't have much lag in game and my ping is usually okay. I'll join the lobby 4-6 seconds late and by then i have to hope nobody has called my favorite position. 90% of the time i'm just stuck with support. I'll be doing drafts until i can find some way to fix it, but i want to just do plain normals without having to worry about joining super late. So basically i press accept, all the little icons fill up, and it stops for a whole 4 seconds. then i join the lobby and all i see is "blue mystified has joined the lobby" or whatever, because i'm the last to join. Is there any way to fix this? it isn't my internet, because i used to play on my brothers computer all the time and it worked like a dream. And it isn't a widespread problem otherwise you would have patched it, so...