One thing to be aware of is the log transfer load. If you look at the log backup sizes over time, in aggregate, you'll get an idea of the network...

Got the offer. Declined the job. Not the money...

SQL is horribly broken. I know...

Contained databases are great, though this means only user/pwd and not AD integrated logins.

One thing I'll try to debug things like this is use a simple command and direct the output to a file. For example:

dir \\MAINDRIVE\subfolder$\dept_folder\Inbound > output.txt

There's nothing you can do from in your existing process if there are rows with a size > 8060. You need to truncate them before they load to ensure the...

I can create this table:

CREATE TABLE MyBigTable2
( myint INT,
  mychar CHAR(8000),
    mydate DATETIME,
  mychar2 VARCHAR(8000),
  mychar3 VARCHAR(8000)
)
GO

Not to press, but this is why we built SQL Clone at Redgate. It allows developers to get a full copy of data with minimal space/time issues.

Run your query without the sum, just get a field or two. Do you get data? I suspect that you haven't structured your query correctly, but if you don't provide...

A few choices I'd recommend:
SQL Skills - https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/enable-encrypted-connections-to-the-database-engine
Brent Ozar PLF - https://www.brentozar.com/training/
Steve Stedman - http://stevestedman.com/consulting/training-classes/
You can also look at...