Here is what Access has to say about the datatype:
Currency values and numeric data used in mathematical calculations involving data with one to four decimal places. Accurate to 15 digits on the left side of the decimal separator and to 4 digits on the right side.
So, the limit would be just under 1 quintillion - ~1,000,000,000,000,000.
I know of no reason why Earth would stop receiving sent packets. How did you determine this was the case?