TCP Retransmission errors to Youtube on Wireless Network

[chmod_net]

Ever since we were trying to setup DNS filtering, on our network, we are not able to browse Youtube.com and not even ping. We reverted back the dns configurations but still can not use YouTube. Restarted DHCP server and WLC but no luck.

Wireshark shows TCP traffic to 208.70.74.21

172.16.0.14	208.70.74.21	TCP	78	[TCP Retransmission] 53468 → 443 [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=64 TSval=110210111 TSecr=0 SACK_PERM=1  TCP Analysis Flag: This frame is a(suspected) retransmission 

$ nslookup youtube.com 
Server: 8.8.8.8 
Address: 8.8.8.8#53 
Non-authoritative answer: 
Name: youtube.com 
Address: 208.70.74.21

Please help!

[TJ-20933766]

This only occurs on the wireless network? Have you tried going to YouTube on the wired network and see if you get the same results?

What solution did you use for DNS filtering and are you certain that you've bypassed it?

Granted that Google owns a lot of servers and IP addresses all around the world but when I do an nslookup for www.youtube.com, I get several IP addresses. Taking one of them (216.58.194.142) & going to https://talosintelligence.com/ and entering that IP address shows the IP to belongs to Google. That makes sense. Now when I enter the IP address that you have, it shows calpop.com. Now this isn't a definitive answer that it's a DNS related issue but it is curious.

Try pinging 216.58.194.142. Do you get responses?

Try opening a web browser and put 216.58.194.142 in the address bar. Do you get to Google?