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Result:

http://erg.biophys.msu.ru/tiki/slot-online.html
Array
(
    [date] => Sat, 03 Jun 2023 02:01:03 GMT
    [server] => Apache/2.4.38 (Debian)
    [content-length] => 283
    [content-type] => text/html; charset=iso-8859-1
)
Array
(
    [url] => http://erg.biophys.msu.ru/tiki/slot-online.html
    [content_type] => text/html; charset=iso-8859-1
    [http_code] => 403
    [header_size] => 161
    [request_size] => 141
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 0.328081
    [namelookup_time] => 0.254259
    [connect_time] => 0.290926
    [pretransfer_time] => 0.291055
    [size_upload] => 0
    [size_download] => 283
    [speed_download] => 862
    [speed_upload] => 0
    [download_content_length] => 283
    [upload_content_length] => -1
    [starttransfer_time] => 0.327792
    [redirect_time] => 0
    [redirect_url] => 
    [primary_ip] => 93.180.23.109
    [certinfo] => Array
        (
        )

    [primary_port] => 80
    [local_ip] => 78.47.42.177
    [local_port] => 34658
    [http_version] => 2
    [protocol] => 1
    [ssl_verifyresult] => 0
    [scheme] => HTTP
)
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>403 Forbidden</title>
</head><body>
<h1>Forbidden</h1>
<p>You don't have permission to access this resource.</p>
<hr>
<address>Apache/2.4.38 (Debian) Server at erg.biophys.msu.ru Port 80</address>
</body></html>
http://erg.biophys.msu.ru/tiki/slot-online.html
Array
(
    [date] => Sat, 03 Jun 2023 02:01:03 GMT
    [server] => Apache/2.4.38 (Debian)
    [content-length] => 283
    [content-type] => text/html; charset=iso-8859-1
)
Array
(
    [url] => http://erg.biophys.msu.ru/tiki/slot-online.html
    [content_type] => text/html; charset=iso-8859-1
    [http_code] => 403
    [header_size] => 161
    [request_size] => 238
    [filetime] => -1
    [ssl_verify_result] => 0
    [redirect_count] => 0
    [total_time] => 0.072977
    [namelookup_time] => 3.2E-5
    [connect_time] => 0.036109
    [pretransfer_time] => 0.03625
    [size_upload] => 0
    [size_download] => 283
    [speed_download] => 3930
    [speed_upload] => 0
    [download_content_length] => 283
    [upload_content_length] => -1
    [starttransfer_time] => 0.072826
    [redirect_time] => 0
    [redirect_url] => 
    [primary_ip] => 93.180.23.109
    [certinfo] => Array
        (
        )

    [primary_port] => 80
    [local_ip] => 78.47.42.177
    [local_port] => 34660
    [http_version] => 2
    [protocol] => 1
    [ssl_verifyresult] => 0
    [scheme] => HTTP
)
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>403 Forbidden</title>
</head><body>
<h1>Forbidden</h1>
<p>You don't have permission to access this resource.</p>
<hr>
<address>Apache/2.4.38 (Debian) Server at erg.biophys.msu.ru Port 80</address>
</body></html>

Fatal error: Uncaught Embed\Exceptions\InvalidUrlException: Invalid url 'http://erg.biophys.msu.ru/tiki/slot-online.html' (Status code 403) in /var/www/oscarotero.com/www/embed3/src/Embed.php:142 Stack trace: #0 /var/www/oscarotero.com/www/embed3/src/Embed.php(81): Embed\Embed::process() #1 /var/www/oscarotero.com/www/embed3/demo/index.php(216): Embed\Embed::create() #2 {main} thrown in /var/www/oscarotero.com/www/embed3/src/Embed.php on line 142