addendum:
Re crimping RJ45 - the better way to do terminations is to use the EZ-RJ45 pass-through plugs like the ones made by Platinum Tools. You need a special crimper, but it's night and day easier. If you're using AWG23 Cat 6, you also need to make sure your plugs can handle those wires (not an issue with the Platinum Tools plugs).
https://en.wikipedia.org/wiki/TIA/EIA-568
"ANSI/TIA-568 recommends the T568A pinout for horizontal cables... The standard also allows the T568B pinout, as an alternative, "if necessary to accommodate certain 8-pin cabling systems"... Many organizations still use T568B out of inertia."
At least, this is true for me. Maybe I did it wrong.
On the other hand, I saw some videos on Youtube of people using other cheap crimpers, and they were getting clean flush cuts. Luck of the draw is a big thing when you get the cheaper tools.
Originally I thought that 1mm or less was preventing my plugs from seating fully but on further inspection I found that the locking lever on my plugs weren't consistently locking. I made the mistake of not using the matching Platinum Tools strain relief boots for my plugs, which actually have a piece of plastic that pushes the locking lever up a little more to ensure a more secure mating between the plug and port.