diff --git a/lib/private/Http/Client/Client.php b/lib/private/Http/Client/Client.php
index a50722d55416c..9b3b34b99d142 100644
--- a/lib/private/Http/Client/Client.php
+++ b/lib/private/Http/Client/Client.php
@@ -56,7 +56,10 @@ private function buildRequestOptions(array $options): array {
 		$defaults = [
 			RequestOptions::VERIFY => $this->getCertBundle(),
 			RequestOptions::TIMEOUT => IClient::DEFAULT_REQUEST_TIMEOUT,
+			// Prefer HTTP/2 globally (PSR-7 request version)
+			RequestOptions::VERSION => '2.0',
 		];
+		$defaults['curl'][\CURLOPT_HTTP_VERSION] = \CURL_HTTP_VERSION_2TLS;
 
 		$options['nextcloud']['allow_local_address'] = $this->isLocalAddressAllowed($options);
 		if ($options['nextcloud']['allow_local_address'] === false) {
@@ -87,8 +90,15 @@ private function buildRequestOptions(array $options): array {
 			$options[RequestOptions::HEADERS]['User-Agent'] = $userAgent;
 		}
 
-		if (!isset($options[RequestOptions::HEADERS]['Accept-Encoding'])) {
-			$options[RequestOptions::HEADERS]['Accept-Encoding'] = 'gzip';
+		// Ensure headers array exists and set Accept-Encoding only if not present
+		$headers = $options[RequestOptions::HEADERS] ?? [];
+		if (!isset($headers['Accept-Encoding'])) {
+			$acceptEnc = 'gzip';
+			if (function_exists('brotli_uncompress')) {
+				$acceptEnc = 'br, ' . $acceptEnc;
+			}
+			$options[RequestOptions::HEADERS] = $headers; // ensure headers are present
+			$options[RequestOptions::HEADERS]['Accept-Encoding'] = $acceptEnc;
 		}
 
 		// Fallback for save_to
diff --git a/tests/lib/Http/Client/ClientTest.php b/tests/lib/Http/Client/ClientTest.php
index dd0e1b7b82217..c4d1ecc4da944 100644
--- a/tests/lib/Http/Client/ClientTest.php
+++ b/tests/lib/Http/Client/ClientTest.php
@@ -284,6 +284,7 @@ private function setUpDefaultRequestOptions(): void {
 		$this->serverVersion->method('getVersionString')
 			->willReturn('123.45.6');
 
+		$acceptEnc = function_exists('brotli_uncompress') ? 'br, gzip' : 'gzip';
 		$this->defaultRequestOptions = [
 			'verify' => '/my/path.crt',
 			'proxy' => [
@@ -291,13 +292,19 @@ private function setUpDefaultRequestOptions(): void {
 				'https' => 'foo'
 			],
 			'headers' => [
+
 				'User-Agent' => 'Nextcloud-Server-Crawler/123.45.6',
-				'Accept-Encoding' => 'gzip',
+				'Accept-Encoding' => $acceptEnc,
+
 			],
 			'timeout' => 30,
 			'nextcloud' => [
 				'allow_local_address' => true,
 			],
+			'version' => '2.0',
+			'curl' => [
+				\CURLOPT_HTTP_VERSION => \CURL_HTTP_VERSION_2TLS,
+			],
 		];
 	}
 
@@ -481,11 +488,13 @@ public function testSetDefaultOptionsWithNotInstalled(): void {
 		$this->serverVersion->method('getVersionString')
 			->willReturn('123.45.6');
 
+		$acceptEnc = function_exists('brotli_uncompress') ? 'br, gzip' : 'gzip';
+
 		$this->assertEquals([
 			'verify' => \OC::$SERVERROOT . '/resources/config/ca-bundle.crt',
 			'headers' => [
 				'User-Agent' => 'Nextcloud-Server-Crawler/123.45.6',
-				'Accept-Encoding' => 'gzip',
+				'Accept-Encoding' => $acceptEnc,
 			],
 			'timeout' => 30,
 			'nextcloud' => [
@@ -499,6 +508,10 @@ public function testSetDefaultOptionsWithNotInstalled(): void {
 				): void {
 				},
 			],
+			'version' => '2.0',
+			'curl' => [
+				\CURLOPT_HTTP_VERSION => \CURL_HTTP_VERSION_2TLS,
+			],
 		], self::invokePrivate($this->client, 'buildRequestOptions', [[]]));
 	}
 
@@ -531,6 +544,8 @@ public function testSetDefaultOptionsWithProxy(): void {
 		$this->serverVersion->method('getVersionString')
 			->willReturn('123.45.6');
 
+		$acceptEnc = function_exists('brotli_uncompress') ? 'br, gzip' : 'gzip';
+
 		$this->assertEquals([
 			'verify' => '/my/path.crt',
 			'proxy' => [
@@ -539,7 +554,7 @@ public function testSetDefaultOptionsWithProxy(): void {
 			],
 			'headers' => [
 				'User-Agent' => 'Nextcloud-Server-Crawler/123.45.6',
-				'Accept-Encoding' => 'gzip',
+				'Accept-Encoding' => $acceptEnc,
 			],
 			'timeout' => 30,
 			'nextcloud' => [
@@ -553,6 +568,10 @@ public function testSetDefaultOptionsWithProxy(): void {
 				): void {
 				},
 			],
+			'version' => '2.0',
+			'curl' => [
+				\CURLOPT_HTTP_VERSION => \CURL_HTTP_VERSION_2TLS,
+			],
 		], self::invokePrivate($this->client, 'buildRequestOptions', [[]]));
 	}
 
@@ -585,6 +604,8 @@ public function testSetDefaultOptionsWithProxyAndExclude(): void {
 		$this->serverVersion->method('getVersionString')
 			->willReturn('123.45.6');
 
+		$acceptEnc = function_exists('brotli_uncompress') ? 'br, gzip' : 'gzip';
+
 		$this->assertEquals([
 			'verify' => '/my/path.crt',
 			'proxy' => [
@@ -594,7 +615,7 @@ public function testSetDefaultOptionsWithProxyAndExclude(): void {
 			],
 			'headers' => [
 				'User-Agent' => 'Nextcloud-Server-Crawler/123.45.6',
-				'Accept-Encoding' => 'gzip',
+				'Accept-Encoding' => $acceptEnc,
 			],
 			'timeout' => 30,
 			'nextcloud' => [
@@ -608,6 +629,10 @@ public function testSetDefaultOptionsWithProxyAndExclude(): void {
 				): void {
 				},
 			],
+			'version' => '2.0',
+			'curl' => [
+				\CURLOPT_HTTP_VERSION => \CURL_HTTP_VERSION_2TLS,
+			],
 		], self::invokePrivate($this->client, 'buildRequestOptions', [[]]));
 	}
 }