What is the purpose of 多 in 你多与别人就此事沟通?
It is a polite way to make suggestions, e.g.

我建议你多运动。
I suggest you to do sports/exercises.  


or

请你多指教。
Please give some guidance/opinion.


So I guess, a more proper translation of you example would be: 'You should contact other people about this issue.'