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Are you sure your ISP did not assign you a new IP? What does this curl show?
curl http://ifconfig.co
Also, I don't see any ports open to your current IP. Usually Synology devices show at least some port available.
I see you have 13 valid certs. So you have no trouble getting certs but have some sort of connectivity problem to your system. Maybe a Synology forum would be able to help more.
Something changed or it would be working. A fresh cert would not cause inbound connections to timeout. And, certs have no impact on HTTP connections. You will need to ask Synology why their renewal process blocked all inbound connections.
Although, I still think it most likely something changed in your router or ISP