I have been on an S1 type for a year.

My spouse has found a new job in a different city in China (Beijing). I have been offered an internship after my S1 type expires. I would like to apply for a visa permitting me to work as an intern for 3 to 6 months.

The company has sent me an invitation letter for internship. What is the best possible way for converting from an S1 type to a work ( internship) Z type?

My S1 type is now due and I have now applied for a 1 month short-term stay visa. I want to apply for the relevant visa in the next month in Beijing.

Is it possible to successfully apply for the work / internship Z type when I get to Beijing? Or would I have to go back to my home country to make the application?
Kind regards
Les