Maintenance for the week of December 22:
• [COMPLETE] NA megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
• [COMPLETE] EU megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
You should post the evidence that this is a server-side issue, and not something that your ISP or some network in-between is screwing up.
If you don't have that, https://pingplotter.com/fix-your-network is a good guide to tracking that down. If you show that it is on the ZOS side, they can't fob you off