Have you tried reinstalling Opera stable in case you have a problem with your profile?
You could also download Opera beta v49 (from which I post this) and see if you still have issues.
Both Opera channels will operate side by side without one version affecting the other.
Only other thing I could mention is that I once had similar issues but it wasn't Opera at fault. At the time I found my WiFi setup was dodgy.
Either way, stick with Opera, as only by raising issues can we, the users, help the developers by passing feedback on this users forum for continuous improvements. (Btw, I am just a long standing Opera user and am not connected with Opera).