Hello I am following a tutorial to pre-process sentinel 3 OLCI data. However after conversion from radiance to reflectance I am unable to locate the Band select option under the heading Raster > Data conversion.
The Band Select operator is only provided with the S1TBX. You can either install this toolbox or use the Subset functionality. With this one you can also select and bands.
You should not update the old SNAP 5 version. It is better to install the new SNAP 6. Major versions need to be installed. http://step.esa.int/main/download/
Regarding the download problem I have no other suggestion as what is already stated in the message