Daisy chaining I2C modules using CAT5 and P82B715
The "L" sides of all three (or more) P82B715's are connected together. So not only do the capacitances add up, but any single device driving the bus low must be able to sink the current through all three (or more) parallel pull-up resistors.

You can just remove the 470 Ω pullups from the slave modules. Alternatively, use higher resistors (e.g., 2.2 kΩ or 4.7 kΩ) everywhere so that the pull-up currents scale with the bus size.

As long as the total bus capacitance is kept below the 3 nF limit, this should work.

If you want to use even more modules, the only way to get this to work would be to use repeater nodes, i.e., two P82B715's in all (or at least some) slave modules.