I have been using this build since it really can route fast, but for some reason it kills my cable modem. Both the good old cisco epc 3208 as well as the annoyingly bad Puma-6 using Compal CH7465LG. They simply die in a very strange way - their web management pages still work, but they refuse to route any new traffic. Ping outside is not working. Restarting the router does not help, but restarting the modem resolves the issue instantly. My ISP spoke with me during the issue and they confirmed even they are unable to connect to the modem when the issue happens. I actually once managed to trigger the issue by simply rebooting the router remotely.
My theory is that somehow it sends some weird packet towards the modem; a packet the modem doesn't know how to handle in such a catastrophical way that it fails and stops working until rebooted. Must be some bug in the modem firmware for sure too because it should never fail this way, but still...
This has never happened before I used this build and also doesn't happen if I connect my PC directly to the modem, so it's definitely something to do with the firmware. I've now switched to Ath79 builds with all kmod packages through opkg [flow offloading] (because I need fast path OR offloading as my internet speeds are 300+ Mbit and sometimes the router is just not fast enough @ stock openwrt). So.. any ideas what this might be? It'm positive it's the firmware because it definitely is caused by the router and it only happens when I am using your build. I couldn't find any info on it anywhere else.