Hey guys, I have been having issues with very high ping when playing Counter Strike.
I am with Orcon, on the 30dl/10ul, unlimited plan with fiber. I am only connected with wi-fi (router downstairs, computer upstairs). 

My ping seems to be fine during the day eg 11am - 4pm, but then from about 5pm -10pm my connection seems very unstable. At 10pm I was in a skype call with a friend and I got 1200+ ping in-game and had to quit. On top of that, every afternoon from about 4pm -10pm i get unstable games that get ping spikes for a couple minutes of 100-200 usually, before returning to an acceptable 30 ping.

I'm wondering what could be causing this to happen because it is annoying only getting stable games in the early part of the day.

My guesses on why I'm getting high ping:

-family members come home from school and get on the internet, watching videos etc making me lag.

-I believe that the latter part of the day is when there is peak internet traffic in my suburb/area which makes the I.S.P slow my connection. 

-Wifi to upstairs + people using internet in my house creates traffic which the router doesn't handle well.

So these are my guesses (which may be completely wrong because I know very little about networking). I welcome any thoughts from people who know more about this kind of stuff than I do as to what could be wrong with my connection. Any suggestions to solve this issue to create a smooth gaming experience in the future would be great also. thanks.