iCloud Photo upload kills network connectivity

Hi there,

I recently noticed a weird issue during my iCloud Photo sync. When the sync progress is running (added a large collection of old photos) my entire network breaks down. The MacBook Pro is connected via 5 GHz WiFi but as soon as I start the sync process (by simply opening Photos) all devices in the network can't communicate properly.

On saturday I married my wonderful wife and today I also wanted to upload some pictures (around 50) and again all devices went "partly" offline. The servers can't be reached anymore. My wife noticed it because TikTok went offline every 1-2 videos and my YouTube stream constantly broke down to 360p with high buffering.

Because it happened twice in several month (first macOS Monterey, today macOS Ventura) I thought it is worth posting here. I also can remember experiencing this issues when iCloud Photo was first published.

Since this could be a bug with high potential to break down enterprise WiFis (hopefully not) I hope someone of you also experienced it.

With best regards

Benedikt