I have made a setup
PPPOE connection on my modem, when my Windows(Win7) booted up, about 5 minutes take time to connect to internet. So other device can deal with internet through WiFi of modem. I'm sure the Windows have a issue.
What is the question exactly? How to delay or is it delaying? You could configure that connection to not automatically connect I believe?
But anyway right now i can see just 3 possible causes that might slow the connection attempt
Your pc itself
While booting, what else is running on the background? Is there any programs in the background that is trying to access the internet? I assume you have not that old computer too?
The server that you are connecting to.
The server just might be busy or having huge load times
Software’s that might conflict
Like firewalls and antiviruses, can you temporally disable them on boot? (Very unlikely but you can try)