Strange. Can you not put the connectors on yourself?
I would doubt that over the distance concerned that the cable type would have much effect but I cannot say that with confidence. Something I learned a long time ago is if something doesn't work the way you want and there is something you know for sure is not right you don't spend time trying to decide if the thing you know isn't right is causing the problem you are having, you just get on and fix the known problem(s). In your case you don't have twisted pairs so fix that. If you still have a problem when you've replaced the cable then come back and ask for more help.