Access to youtube and facebook on my apple mac is blocked

[#1]

Does anyone know how to cure this problem? All of a sudden I cannot access youtube and facebook on my apple mac (the strange thing is that my PC is unaffected)

[#2]

Hi robyn,
Can you confirm if you can ping both youtube.com and facebook.com from your Mac?  You will need to open a Terminal window (Applications Folder -> Utilities -> Terminal) and type:
ping www.youtube.com
Or:
ping www.facebook.com

[#3]

Yes. I can access them from your links. 

[#4]

what happens when you try to go onto the sites Robyn?
(error number? timeout? etc.)
Thanks

[#5]

Quote from: robyn

Yes. I can access them from your links.

Just tried the terminal thing now and it just keeps continuing like this Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
Request timeout for icmp_seq 4
Request timeout for icmp_seq 5
Request timeout for icmp_seq 6

[#6]

They just time out.
Now and again I can get access to youtube, but once something is loaded and I do another search I lose access again. This is driving me crazy.
I have tried reinstalling flash player, changing the MTU setting to 1400 as recommended, turning on and off the router, different browsers (safari & google chrome), removing DNS server addresses - all to no avail. Please can you help? I am really stuck with this. :

[#7]

I'm not trying to be awkward or pedantic.. just not getting much information from your posts
Are you able to connect elsewhere (google? etc.)?
are you connecting to your network via Wireless or Wired?
What router do you have?
have you tried accessing the sites on the PC at the same time as you cannot on your mac?
Is anything else running (Time Machine?) - this could have an affect on network performance
Thanks

[#8]

Are you able to connect elsewhere (google? etc.)? - My problems only apply to youtube and facebook
are you connecting to your network via Wireless or Wired? - Wireless - via Airport
What router do you have? - TP-Link
have you tried accessing the sites on the PC at the same time as you cannot on your mac? -Yes - no problem
Is anything else running (Time Machine?) - this could have an affect on network performance - No all other programs are closed
Occasionally I can get access and then when I do another search the connection just goes on youtube

[#9]

Quote

changing the MTU setting to 1400 as recommended,

1400 is pretty low, where did you find that recommendation? 1492 i believe is the 'recommended' for ADSL connections - setting 1500 will have no adverse affects.

Quote

I am really stuck with this.

I can see why, very strange issue indeed, by "removing DNS addresses" you mean you now have none set?
can you get to www.youtube.com/html5 - try running the HTML5 version of the site if you can and see if the problem remains.
Regards

[#10]

I have reset the MTU as before and the DNS addresses. Have reset the router and done a speed test on my broadband connection which is 2.78 mbps. Spoke to Apple who said they think this could be the problem, but I don't believe it as youtube worked no problem before.
have tried www.youtube.com/html5 - this doesn't work either.  I really appreciate your help ..................................... any other suggestions?

[#11]

The next best thing is to try and traceroute to youtube.  Again open a Terminal window (Applications Folder -> Utilities -> Terminal) and type:
traceroute www.youtube.com
And press "Enter" on your keyboard.  We will need to see the full output for this one so take a screengrab or copy and paste the text directly from the Terminal window.

[#12]

Robyn$ traceroute www.youtube.com
traceroute to www.youtube.com (78.16.49.15), 64 hops max, 52 byte packets
1  192.168.1.1 (192.168.1.1)  1.095 ms  0.866 ms  1.287 ms
2  lo0-central4.ptn-ag04.plus.net (195.166.130.82)  22.663 ms  17.832 ms  16.067 ms
3  gi2-23-442.ptn-gw02.plus.net (84.93.253.75)  16.782 ms  15.723 ms  14.990 ms
4  linx-gw.uk.esat.net (195.66.226.65)  15.337 ms  15.543 ms  16.041 ms
5  pos1-3-1.br002.cwt.esat.net (193.95.131.49)  32.269 ms  32.550 ms  32.127 ms
6  teng0-0-0-3.core001.cwt.esat.net (193.95.129.56)  33.145 ms  33.191 ms  32.052 ms
7  teng0-1-0-0.rt502.cwt.esat.net (193.95.129.70)  32.630 ms  33.544 ms
    teng0-0-0-0.rt501.cwt.esat.net (193.95.129.64)  32.898 ms
8  gige1-0-0.bas508.cwt.btireland.net (193.95.136.117)  31.995 ms  32.580 ms  32.723 ms
9  * * *
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Does this help?? Thanks

[#13]

That is odd as I get something totally different using Plusnet as Primary DNS and Google as secondary DNS
C:\Users\Jim>tracert www.youtube.com
Tracing route to youtube-ui.l.google.com [74.125.230.135]
over a maximum of 30 hops:
  1    <1 ms    <1 ms    <1 ms  192.168.0.1
  2    33 ms    32 ms    33 ms  lo0-central2.thn-ag2.plus.net [195.166.128.230]
  3    33 ms    32 ms    31 ms  gi1-14-221.thn-gw1.plus.net [84.92.6.200]
  4    31 ms    32 ms    31 ms  72.14.222.97
  5    37 ms    32 ms    33 ms  64.233.175.27
  6    32 ms    32 ms    32 ms  209.85.251.202
  7    33 ms    33 ms    32 ms  74.125.230.135
Trace complete.

[#14]

Well I don't know a lot about programming so have no idea what your results mean. All I want is access to youtube?

[#15]

It means that my system is seeing a totally different address for YouTube and it appears that it may be a virtual link via Google.
Can you try the same thing from the PC