Comment by kjs3

You can block at your gateway/router. Lots of places have country IP ranges[1], and there are even more or less frequently updated lists of 'malicious' IP ranges[2]. Some gateway providers include 'block by country' and/or 'download blocklists automatically' as a feature.

[1] e.g. https://github.com/ipverse/geo-ip-blocks

[2] e.g. https://github.com/bitwire-it/ipblocklist