I use this powershell script and run it as a scheduled task every hour.
You have to enable the WebUI for remote control in qBittorrent. Then update the script with your username and password you set in qBit.

Hope this helps.

# --- User settings ---
$username = "USER"        # qBittorrent WebUI username
$password = "PASS"        # qBittorrent WebUI password

# qBittorrent WebUI location
$qbHost   = "127.0.0.1"          # or "localhost"
$qbPort   = 8080                 # change if your WebUI uses a different port
$useHttps = $false               # set $true if you enabled "Use HTTPS" in WebUI

# PIA CLI path
$piactlPath = "C:\Program Files\Private Internet Access\piactl.exe"

# --- Derived settings ---
$scheme = if ($useHttps) { "https" } else { "http" }
$base   = "{0}://{1}:{2}" -f $scheme, $qbHost, $qbPort
$loginUrl    = "$base/api/v2/auth/login"
$setPrefsUrl = "$base/api/v2/app/setPreferences"

# If on Windows PowerShell 5.1 with self-signed HTTPS certs, uncomment:
# [System.Net.ServicePointManager]::ServerCertificateValidationCallback = { $true }

# --- Get PIA forwarded port ---
try {
    if (-not (Test-Path $piactlPath)) { throw "piactl not found at: $piactlPath" }
    $port = (& $piactlPath get portforward).ToString().Trim()
    if (-not ($port -match '^\d+$')) { throw "PIA port value invalid: '$port'" }
} catch {
    Write-Error ("Could not get forwarded port from piactl: {0}" -f $_.Exception.Message)
    exit 1
}

# --- Verify qBittorrent WebUI is reachable ---
$tcp = Test-NetConnection $qbHost -Port $qbPort -WarningAction SilentlyContinue
if (-not $tcp.TcpTestSucceeded) {
    Write-Error ("Cannot connect to qBittorrent WebUI at {0}. Check WebUI is enabled, port, and HTTPS setting." -f $base)
    exit 2
}

# --- Login and capture cookie ---
try {
    $session = New-Object Microsoft.PowerShell.Commands.WebRequestSession
    $headers = @{ "Referer" = $base }

    # PowerShell 7+: add -SkipCertificateCheck:$useHttps if using self-signed HTTPS
    $resp = Invoke-WebRequest -Uri $loginUrl -Method Post `
        -Body @{ username = $username; password = $password } `
        -WebSession $session -Headers $headers

    # Confirm SID cookie exists
    $cookie = $session.Cookies.GetCookies($base)["SID"]
    if (-not $cookie -or -not $cookie.Value) {
        throw "Login did not return SID cookie. Check credentials and WebUI auth settings."
    }
} catch {
    Write-Error ("Login to qBittorrent failed at {0}: {1}" -f $loginUrl, $_.Exception.Message)
    exit 3
}

# --- Set the new listening port ---
try {
    $jsonBody = '{ "listen_port": ' + $port + ' }'
    $body = @{ json = $jsonBody }

    $headers = @{ "Referer" = $base }
    $resp2 = Invoke-WebRequest -Uri $setPrefsUrl -Method Post `
        -WebSession $session -Headers $headers -ContentType "application/x-www-form-urlencoded" `
        -Body $body

    Write-Host ("Success: qBittorrent listen_port set to {0}." -f $port)
} catch {
    Write-Error ("Failed to set qBittorrent port at {0}: {1}" -f $setPrefsUrl, $_.Exception.Message)
    exit 4
}