Name of ISP
Comcast /Xfinity

Country of Residence
United States

When does the problem occur (always, only during specific times?)
Pretty much all the time. Not so much during mornings, always bad during afternoon/night. Dungeons/instances are impossible during these times. There is a 5-10 second delay when moving/casting spells. The game is unplayable during these times.

Reference number from your ISP, if you raised this matter with them
Comcast /Xfinity says they are not the problem. They are not throttling. The problems lie with SE.