Hi ,
You can configure the restrictions for your VPN subnet on the firewall level or on network devices.
In your case, some third-party firewall might be easier to achieve your goal. For your reference:
https://www.draytek.com/support/knowledge-base/6001
Please Note: The third-party products discussed here are manufactured by companies that are independent of Microsoft. We make no warranty, implied or otherwise, regarding these products' performance or reliability.
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Best Regards,
Candy