Just to inform you i did go back to the 1.31EU version but found that it was not stable (enough).
Running 1.33NA regular release (same as latest beta) and in general above 1 day uptime.
Also note that my A4 seems to suffer from heat issues. Mounted a CPU blower to keep it cool.
Fortunately the router was a gift from a colleague so for me it is an experiment to try anything that makes it work:)
My A4 is standing upright in its stand for better heat dissipation and it won't become to hot.
But as I saw there are same ceramic heatsinks mounted on CPU and switch - and perhaps not the best

So if its only an experiment for you, you may try to exchange them with a chipset cooler set (Coolermaster, Zalman, Revoltec etc.). I have good experience with this cooling down my older NAS CPU.