rc.local is not synchronised to the network going up in any way - on my systems rc.local has always run before the network is up. It waits until the network manager starts, but not for the network to actually go up.
If you want to run services after the network is up your best option is to enable “wait for network” in the networking GUI, then create a systemd service to run your scripts, and specify:
After=network-online.target
Wants=network-online.target
In the [Unit] section of the service.
Another option is you could change rc.local to not run until the network is up by creating a file called /etc/systemd/system/rc-local.service.d/local.conf and adding only these lines in it:
[Unit]
After=network-online.target
Wants=network-online.target
This will delay all scripts run by /etc/rc.local until the network is up, or after a 60 second delay if the network never comes up.