Modpacks aren't working?

For some reason, whenever I try and start my server with any of the modpacks installed, such as pixelspark, or any of the FTB modpacks, it says Cannot connect to server. I have checked multiple times to make sure my server is online so that I can join it, but no matter what, It always says cannot connect to server. When I am running normal vanilla minecraft, this doesn't happen, and with pixelspark I try and go into it after I have changed my minecraft to the proper version, and the game gets stuck in the loading screen for 6-7 minutes before my server times out. Please help! thank you!

Wait I can enter the dyn IP instead of the other IP? and when I Try to play any of them, It doesn't work, I tried using forge mod loader aswell for some of them, and it said "These modpacks could not be found." and yada yada .-. all I want to play is pixelmon, but it won't work and I don't know why,could someone give me a full step-by-step, because i try playing pixelmon in 1.8.6, can't do that, so i go to 1.7.10 which should work, and it just gets stuck in the loading screen and i can't do anything...