iPhone SE 2023 iCloud Photos slow on Wi-Fi, fast on data

Hello everyone!

I recently turned on iCloud sync for photos to save space on my phone, and for some reason the sync process is painfully slow on my home WiFi, but runs normally while I am on data out of the house. I have ~15,000 items to sync, and since starting the sync on Sunday my phone shows that only ~3,500 items are on iCloud, with 98% of that sync happening while I am on mobile data.

I don’t normally plug my phone in to charge while at work, but this week it has been a necessity because my phone will drain the battery aggressively working to sync everything. I will check in throughout the day and see the number of photos synced increase by several hundred over the course of a few hours.

When I get home, my phone will sync hardly any photos at all. Last night before bed, I was at 3,486 items synced, and this morning after having the phone connected to WiFi and power all night with no other apps running, I am at 3,503 items synced.

Does anyone have any insight into why this could be happening? I cleared storage space a couple days ago to get up to 12GB free on my 128GB iPhone SE 2023, I have 100 GB of iCloud storage left on my 200 GB plan with all my photos together being around 60GB, I am not connected to a VPN, I selected the Optimize iPhone Storage option in the iCloud photo settings, I have fast WiFi up/down that has no issue with multiple streams/video calls running at the same time on different devices in the house, but my phone still makes very little progress syncing over WiFi. Any help would be appreciated, thank you!