I've been looking for a way to have a serial connection for my Linksys EA8300 routers, as I am planning to build custom firmwares for it (as for my Linksys WRT3200ACM, which luckily has pins for a serial connection already exposed), so in case things go south, I'd like to have a fallback/troubleshoot plan.
Opening up the EA8300 was easy enough, however there seems to be some "material" in the pin holes, which prevents me from sticking pins through them and soldering them from the back.
Please see the following image (taken from https://openwrt.org/_detail/media/linksys/ea8300_pcb_top.jpg?id=toh%3Alinksys%3Alinksys_ea8300 and zoomed in)
I don't think it's soldering tin, as I have been unable to desolder/free up the pin holes, but I might be wrong, as I am not an expert in soldering.
Finally, to my question:
How have you guys realized serial connections to the EA8300? Have you just soldered some wires onto the pin holes or did you drill through the holes and afterwards soldered some pins on it - or maybe just soldered the pins onto the holes?
.. or am I just too stupid to remove the soldering tin from the holes?
Every help is highly appreciated - thanks a lot beforehand!