When your connection drops or starts to drop you can ping your isp host / dns server.
It should be something like this : ping 172.16.0.1 -t
Don't forget to add the space before -t
If there's no connection there should be a request timed out reply or network unreachable.
This will let you know if your ISP is outright dropping your connection or just capping your data download.
If you get constant good replies like : Reply from 172.16.0.1 bytes = 32 time =1ms TIL =64 without any interuptions then you have a steady connection and then the problem can only be resolved by the ISP.
You might want to log into the control pannel to check if you have put any data limit filter on yourself by mistake.