Internet connection isn't working properly

Hello one and all.

Lately, I have been experiencing problems with wifi connection on my MacBook Pro 13' Late 2013.

Few times a day, my MacBook does seem to lose internet connection, wifi switches to my neighbour's router. When I switch it back to mine, it doesn't load anything from Safari, Chrome. Dropbox icon on the menu bar is also gray and shows no connection. It lasts for about 1-2 minutes and it goes back to normal.

I was convinced that it had been my internet provider's fault. I ran a ping command in Terminal and the results kinda shocked me. When experiencing the problem, there is in fact request timeout for a few seconds, but then it reads ping again - everything seems normal in the log, but browsers, Dropbox app don't load anything (like I wrote before). On my iPhone (connected to the same router) everything is fine. After 1-2 minutes everything works again.

/Also: I started noticing the problem about 1/2 months ago and I always update Mac OS.

If it is possible, I would like not to reinstall whole system.

Thanks in advance!