improve error msg obscure when connect url port miss

[camilesing]

see #768

[majst01]

Thanks for your first contribution, appreciate that.
You should leave formatting as is, and change only what is required what you want to achieve. Otherwise reviewing is not possible.

Also "*" imports are not accepted in the project

[camilesing]

Ok, I did @majst01

[majst01]

Will review after release in the next days, be patient

[camilesing]

@majst01 Er, I think it's a great improvement, it can void someone to take sometime get understand why client not work. so it should merge to the next release version. what do you think?