Mods aren't loading

Dear Nitrado Support Team,
I have rented a Minecraft server so that I could play modded Minecraft with my friend. I originally rented it as a Minecraft Vanilla server, but I have changed it to a Minecraft Modpack server afterwards and downloaded Forge 1.7.10, since all my mods are on 1.7.10 (I have tried the modpack in singleplayer and it worked). So, I first tried the method to upload files on your site and then I used Filezilla, but both times the mods wouldn't load or I would get a connection error, now I don't know what to do. Can someone help me out?

Here's what I mean:

I'm pretty sure that my client is compatible with the server, I have checked the mods and the version.

Okay, thank you