No more boot-every-15-minutes for me!
Turns out something was wrong with the Linksys router I have. I disabled that and hooked the ethernet directly to the motherboard. While it doesn't actually solve the problem, it works for now. No boots at all today.
This was discussed in the beta forums at
http://planetside.station.sony.com/beta . Some network engineer went through all the details. Something to do with Firmware version 1.42 (over my head). But the good news is..... no boots!