I'm also in Southern California on COX and have had horrid lag for the last week+ and have tried everything to fix it including calling our ISP. Nothing has worked.

Platform? Windows
Have you tried using a wired connection? Only play on a wired connection
Internet Service Provider: Cox
Region/Location: Southern California, San Diego County
Separate Modem and Router or Hybrid? Separate Modem and Router
Are you using a Firewall/Anti-virus solution? Windows defender
Does the issue only happen with specific characters or all characters? I play on one character on Aether