The problem is not with the Auto Filter drop-down.
It is likely that the 'numbers' 110 to 775 are actually text that looks like numbers.
The drop down has sorted numbers before text.
If your list of numbers starts in cell A2, enter this in cell B2:
Drag this formula down alongside all your list of numbers.
Now copy these cells in column B
Select cell A2 and 'Paste Special...' and select Values and click OK
You can now delete the formulas in column B.
Test your auto filter again.
Hope this works!