I agree with Pinski1. Those soldered joints ain't up to spec.

For that kind of work I use a cheap 100W Ironside Soldering iron with the thinnest point I could buy for it.
(for heavier work I have other points, up and including rather heavy copper blocks, electrocoated with nickel)

I'm tempted to buy the 150W brother of it...

I also use custom made teflon clamps to keep the connector pairs in a solid lock. (handy if you can make those yourself from billet or sheet)

Another investment I can advice, heatshrink in the right dimensions. It can hide a lot of sins.
The alternative is hotglue.