Main office and two branch offices each connect directly to the internet. Branch routers are endpoints for a VPN to the main office and a site-to-site VPN to Azure. QoS rules on branch routers are shown in the table. Users report slow responses and connection errors to Azure Virtual Desktop. Which rule should have its bandwidth allocation increased to improve Azure Virtual Desktop performance?

Rule3 allocates bandwidth for traffic to Azure Virtual Desktop (AVD) over the site-to-site VPN. Increasing its bandwidth allocation directly addresses performance issues for AVD users. Rule1 is for general internet traffic, which doesn't directly impact AVD performance over the VPN. Rule2 is for traffic to the main office over the VPN, not AVD. Rule4 is for local network traffic, which is irrelevant to AVD connectivity issues over the internet and VPN. Therefore, optimizing Rule3 is the most effective solution.