Hi Sirius - you've basically got too many things trying to happen all simultaneously to make a good surface out of that.

You've got a 5-sided boundary, you've got a lower piece that kind of protrudes suddenly, and on top of that you have some sharp corners in the middle of some shapes. Each of these things adds a kind of complexity to the layout.

You're generally better off trying to build a single surface with sweep or network out of a single smooth piece rather than trying to force so many different kinds of variations into a single surface creation command.

When you have something like a piece that kind of suddenly protrudes from another one, it's generally better to build that as a separate object and then fillet them together.

Otherwise to actually build a network or sweep directly would require adding in some more in between curves along the lines of what Mike is showing above - another possibility is attached here.

But I'd probably try more to build it more as separate pieces and either fillet or blend them together rather than trying to build that whole thing in one sweep.

- Michael