Thanks for the answer, now I understand how the ports work better, any ideas to lower the latency?
Ckpool is one of the few addresses that gives me high latency, I am beginning to believe that it will be from my ISP, but I have few options to change providers.
It's highly unlikely to be an ISP related issue, it's mainly about your geographical location and the distance between your miner and the pool's server, someone who lives next door to wherever the server is located will have less latency then someone with 10x faster internet connection but lives on the other side of the world.
As far as I know CKpool has a single server in the U.S, the other large pools have different servers in different locations which is probably why you are getting better results in terms of "ping", but, you need to be really far and have a shitty connection to have a ping high enough that would affect your mining operations, it isn't exactly accurate to just ping a pool's website, but it's good enough to get some results, so if you ping Ckpool and it doesn't take more than 200ms or so, you are good.
I personally tried mining to a PPS pool while being behind a VPN of another country in a different continent, mining to a pool in a completely different continent on the other side of the planet, and my rejected/stale shares were close to zero, the overall ping for that route was no less than 300-400ms and it was all good, I am not telling you it's perfectly safe to mine with 300ms, most pool operators won't take the risk of giving the green light because nobody wants to be held responsible, so they will generally tell you to try and keep it below 200ms (most of them won't even give you a number, to begin with), but based on my own personal experience, you will be good with up to 300ms, if you could bring it down to 30ms, ya even better, if not -- still works.