The v17.0 P2Pool binary that you downloaded does not have veqtrus' Don't mine segwit txs for now compatibility patch. The v17.0 P2Pool binary on mainnet's GitHub releases page similarly does not have veqtrus' compatibility patch. That is why your P2Pool node is having trouble syncing with mainnet, as mainnet's sharechain has not yet been forked/upgraded to support segwit transactions.

You have two options to get P2Pool v17 working on your Windows PC:
1. Wait for forrestv to publish a new up-to-date v17.0 binary that contains veqtrus' compatibility patch, or
2. Run P2Pool v17 from source.

There are two ways to run mainnet P2Pool v17 from source on Windows:

1. Download a ZIP file of mainnet P2Pool's master branch by going to https://github.com/p2pool/p2pool, clicking the green Clone or download button on the right side of the page, and then clicking Download ZIP. Unzip the downloaded file to your preferred location. Navigate to your P2Pool folder, right-click on the folder while holding down the Shift key, and then click Open command window here. Then type python run_p2pool.py (along with your desired parameters; these can be found by running python run_p2pool.py --help) and hit Enter. Make sure that you have installed the necessary bits of software before doing all of this.

2. Cloning mainnet P2Pool's master branch using Git. To do this, you must first install Git if you haven't done so already. Once you have installed Git, go to or create a folder where you would like to have your P2Pool files in. Then, right-click on that folder while holding down the Shift key, and click Open command window here. Then, type git clone https://github.com/p2pool/p2pool.git and hit Enter. This creates a new folder with all the P2Pool files in it. Then, to run P2Pool, simply right-click the P2Pool folder while holding down the Shift key, click Open command window here, type python run_p2pool.py (along with your desired parameters; these can be found by running python run_p2pool.py --help), and hit Enter. Again, make sure that you have installed the necessary bits of software before doing all of this.

Option 1 (downloading a ZIP file of P2Pool's master branch from its GitHub page) requires you to download a new ZIP file every time P2Pool's master branch is updated with new commits, if you want to keep your local P2Pool up-to-date.

Option 2 (cloning P2Pool's master branch using Git), on the other hand, enables you to update your local P2Pool by simply navigating to your P2Pool folder and running git pull from the command-line.

If you're feeling adventurous, there is also the option of using the Windows Subsystem for Linux to run your Bitcoin full node and your P2Pool node Ubuntu-style, but without having to run Ubuntu as a virtual machine.