I'm not on static ip.
Earlier I had bsnl and there was rarely an issue, maybe monthly once for few hours. My neighbors have jiofiber, their downtime is low.
Airtel takes atleast 1 day to resolve the issue.
One thing I observed is, someone in neighborhood complains to airtel that internet is down. They come and resolve for them. In few hours, our internet does down. I've been observing this pattern since few months. This isn't the reason all the time, but happens regularly.