Can I use the same individual 401k to receive contributions of income from (1) unincorporated sole proprietor income and also (2) single-member LLC?

I provide consulting services as an unincorporated sole proprietor.  I have  a longstanding individual 401k for this business endeavor.  The 401k is a prototype "super simplified standardized individual 401k profit sharing plan" with a brokerage.

I have another service business, in a different field, which is organized as a single-member LLC.   There are not retirement plans specifically associated with this business.

Can I contribute income from business