Hello
i am new here, and quite new to electronics. as such i am still pretty much at the level of standard passive components, and just play abit with timers and such.
i have a made a small project where i am connecting a small router to the a plug that contains 24Vdc and an ethernet connection. the small router i am using is running on 5Vdc (usb) so i have a small buck converter inbetween to step down the voltage from 24 to 5.
unfortunaly i keep burning up buck converters at random, some times they last 3-400 times, and some times they only last a couple of times.
from what i have been able to figure it, it must be due to a spike during when i plug it in. it is allways at the point of plugging it in that the converter gives up.
i have installed a diode on the negative to protect from reverse polarity connection (1N4007), and i tried installing a zener diode across the supply to cap the spike (1N5360BG).
this also seems to fix the positive spike, but i still get a negative spike from time to time.
i have tried multiple buck converters (all cheap chinese ones) and it is allways the IC on them that blows up, not sure if you can use the markings on them for anything (JWBV 045F, AGCH, 1HRG, MP1584EN, CXW8509) i have tried to look up a datasheet, but without much luck

so the big question is, how do i create a proper filter to protect the buck converter or maybe someone can point me towards a better buck converter.