ne know of any app that can monitor broadband connection. Ideally something that does a scheduled speed test every 15 minutes. Something like that ?
Could use: https://samknows.one/hc/en-gb/articles/360000451757-What-is-the-Whitebox-
If you use your own router and can allow ICMP requests you could also use: https://www.thinkbroadband.com/broadband/monitoring/qualityThis doesn't perform a speedtest but monitors latency
Otherwise you can create your own app/script if you have the knowledge of doing so.