We recently had a client install a new AT&T Fiber line for Internet access. After the line was installed, it didn't work properly. AT&T did some troubleshooting and said the line was OK. I performed some troubleshooting and noticed that one of the DNS servers 220.127.116.11 that AT&T provided was randomly timing out during a simple ping test.
I changed the DNS fowarders on the client's DNS servers to 18.104.22.168 (AT&T), 22.214.171.124 (uu.net) and 126.96.36.199 (uu.net). After this change the Internet connection was fast and stable.
If your environment is configured to use 188.8.131.52 as a DNS Server and you're having problems reaching sites on the Internet, consider removing this DNS server from your configuration and use a different ISP's DNS server.