We had the exact same problem when offering managed services. Having owned both an ISP (Internet service provider) and MSP (Managed Services Provider) businesses, it was always found that a mix is usually required.

There are some very nice open source and paid RMM solutions that can give you some of what you need. Just use your favorite search engine and look for words like ‘RMM’, ‘remote Internet monitoring’, ‘Logging Internet outages’ and other similar terms and you’ll find a number of solutions that can help.

There are many good review sites that compare Internet monitoring solutions.

Of course, part of the decision making process is budget as well as complexity.
How much will it cost? Can the solution give you a way to ramp up without a large up front budget? How long will this take to implement? How quickly will our IT personnel understand how to use the solution?

As an MSP, for us, there was nothing that did exactly this and we ended up developing our own solution after trying many that were either too costly, too complex or simply didn’t give the granular information we were looking for.

We eventually started offering it as OutagesIO and understanding the questions above, we built it so that there are no large up front costs, it easilly ramps up as needed and it works stand alone or alongside existing monitoring solutions. 

OutagesIO monitors each connection from that locations point of view, logging any and all problems saving countless truck rolls by confirming or eliminating Internet problems as a cause of downtime.

Trying OutagesIO is as easy as creating an account, installing an agent on Windows, Linux, Raspberry and other ARM devices then allowing the data to start coming in showing how this connection is doing.