CAN bus with star configuration/long stubs
Try a termination on the end of EACH of the 2.5 meter branches, like this







simulate this circuit &ndash; Schematic created using CircuitLab

You likely will need to alter the 47pF. Over 16 branches, this is 750pF, well under the 2,200pF I computed as the maximum C_can_buss_all_causes.
Larger branch C (47 -> 56 -> 68 -> 82 -> 100pF) become better at dampening, and provide a cleaner data-eye, but SMALLER amplitude. Thus you need to experiment; maybe install TRIMMER caps (10pF -100pF)on your PCBs.

The max length is 2 branches * 2.5 meters each or 5 meters. The STAR reflection time is (assuming 30 nanoseconds round trip for each branch) 2 branches * 30nS or 60nanoSecond; this is twice as fast as the 130 nanosecond
RC timeconstant I computed in the top TEXT in the diagram.