problems of fluctating hashrate

[ludbega]

hi, i'm a newbie in minig and I have a Asus R9 280x-DC2 T and when i try to mine in a pool, my hashrate isn't stable sometimes he is up at 2200kh/s and over times he is down to 150 kh/s.
i think it could be the internet connection, my computer is far from the modem.
it's not a problem of speed but more some  interuption in the connection, 1-2 per hour.
it's seems to be the only problems that i have, is it normal that it's fluctuating or should i be concern about my connection to the modem?