This is trickier than you would think. Here’s my personal instructions to activate legacy mode on a module. It does work…
go to:
config/services/module/module_routing.yaml
then repair→rebuild in admin ./bin/console cache:clear from cli
First of all, if you want it to use the legacy module set it to “false”, it seems counterintuitive as it’s called “legacy module routing” you’d expect it to be the opposite.
ALSO… all the module names in the file are in lower case ie: “accounts” when they are actually “Accounts” in SuiteCRM, so if you have a custom module, you’d expect it to be lower case. You’d be wrong. I have “PLNE_Planes” module and you have to enter it exactly as it is in SuiteCRM custom modules folder.
ALSO… do not “tab” in the file to line up the columns, will not work. Space bar only.