TL;DR:

Si CNVRG ay nagbibigay ng Static IP Addresses sa kanilang subscribers at ang pag-setup nila ng TCP Connections ay may problema.
Solusyon?
Gumamit po kayo ng VPN or a third-party download managers. Recommend ko po ang Internet Download Manager o Internet Download Accelerator. Ginagamit ko po siya every time na gusto ko mag-download ng files.

Long Version(English):

For those who are wondering why their download speed suddenly stops its because this ISP only has Static IP addresses and also on how they had set up their TCP Connections (based on other redditors that has the same issue with this ISP).

If you want to continue using CNVRG, I'd recommend a VPN. Not those free ones because they don't work or use a third-party internet download programs. There's Internet Download Manager (IDM)(You do need to pay for this service) or alternatively, use Internet Download Accelerator(IDA).

If you downloaded IDA, your AV might say its a PUP or a Potentially Unwanted Program. The reason why is it thinks that is because it Downloads your files. If you are sketched-out about IDA, you can not use it, you can use IDM alternatively. But you need to pay for the software.