This modbus T-junction VW3A8306TF03 or VW3A8306TF10 the maximum length of cable that you can use between two T-Junction box is 10 meters as the ports of this modbus T-junction VW3A8306TF03 or VW3A8306TF10 were isolated ports and this is the limitation of this isolated port.
If you wants to increase the length then he can use two numbers TWDXCAISO (serial link tap isolation box) between the two  modbus T-junction VW3A8306TF03 or VW3A8306TF10 using which this maximum distance can be increased to 1.2 KM.

Released for:Schneider Electric India