src/Selenium/SeleniumServerAdapter.php
public function isAccessible(): bool
    {
        // Check connection to server is possible
        $seleniumConnection = @fsockopen(
            $this->serverUrlParts['host'],
            $this->serverUrlParts['port'],
            $connectionErrorNo,
            $connectionError,
            5
        );
        if (!is_resource($seleniumConnection)) {
            $this->lastError = $connectionError ?? 'unknown connection error';

            return false;
        }
        fclose($seleniumConnection);

        return true;
    }
public function isAccessible(): bool
    {
        // Check connection to server is possible
        $seleniumConnection = @fsockopen(
            $this->serverUrlParts['host'],
            $this->serverUrlParts['port'],
            $connectionErrorNo,
            $connectionError,
            5
        );
        if (!is_resource($seleniumConnection)) {
            $this->lastError = $connectionError ?? 'unknown connection error';

            return false;
        }
        fclose($seleniumConnection);

        return true;
    }
Test if server URL is accessible and we can connected there