Hey purgatory,
Thank you for reaching out! This is certainly not a side effect from the upgrade. I have Internet 150 personally and with the upgrade, I do not see any change in the upload speeds. I have not heard of any reports of a known issue, it is likely a signal related issue to your home or area.
Do you have any other special settings with the Shaw modem or 3rd party routers/switches attached? What other troubleshooting steps have you tried with the support team member?
Cheers,
Tony | Community Mod.