My apologies you are experiencing high pings and buffering issues.
Looking at your connection, there is a high peak time traffic fault in your area which can cause slow speeds and issues with latency/ping times. The reference number is F004106196 and has a review date of 5th April.
I know you mentioned that the router is downstairs and you are using a wireless connection, however are you able to complete ping tests/trace routes whilst wired outside peak hours for us to take a look at please?
Wish it were possible but there's no way for me to connect wired, the computer is upstairs and the router is down and you say there's a traffic fault in my area does that mean I'm entitled to the credit people recieve when they have a traffic fault?