An intermittent connection problem is difficult to explain from memory. A short log can reveal whether interruptions follow a pattern and gives support staff a more useful starting point.
Record the date, approximate time, affected device and location. Describe what failed: a call, one website, an application or all internet access. Note whether another device experienced the same issue at the same moment.
Keep observation separate from explanation. The phrase video call froze at 19:10 describes an event; the router is broken is a conclusion that needs evidence. This distinction prevents an early guess from shaping every later test.
If you make a routine change suggested by your provider or manufacturer, record it and observe the result before making another change. Several simultaneous adjustments make it harder to know which one mattered.
After several incidents, summarise the common features rather than sending a huge unfiltered diary. A clear timeline can help identify the next useful check, even when it does not establish a cause by itself.