I beg to differ here, the ipq806x platform is stable - I've had continuous uptimes of several months (and only interrupted by conscious firmware upgrades or power outtages/ blown fuses). There may be an issue with stmmac and certain packet sizes >= 1500 bytes, but you either have them (because your ISP modem is configured to use them), or your don't (and this issue is very likely to affect many more targets than just ipq806x, as stmmac is a very common IP core).