Yishan Road on Line 9 cannot be changed directly now. After Line 4 arrives at Yishan Road, you can take the ferry to Guilin Road for free and transfer to Line 9 (you can take the ferry to Guilin Road according to the signs).
Then take Line 9 to Songjiang University Town, and then transfer to Songjiang 18 Road to the University Town.
The last bus of Songjiang University Town on Line 9 is 2 1:04.
The total time from Xujiahui to Yishan Road is 15 minutes, and the most important thing is the ferry to Guilin Road, which may be between 5- 10 minutes, and Guilin Road to Songjiang University Town is 43 minutes.
It takes 1 hour and 15 minutes in total.