I have an issue with my S20 Ultra not downloading images/videos/gifs on WhatsApp when connected to WiFi. As soon as I turn off WiFi they download on 4G.
WhatApp support suggests its likely an issue with SD cards but the folders are on the internal storage.
I have other devices that have no issues on the same WiFi network.
If the download over Wi-Fi option is selected in WhatsApp and this occurs with multiple Wi-Fi routers, it is an issue with the WhatsApp. Have you tried re-installing it?
I have the same.issue here... i use s20 plus... the image file only loads when I'm on 4g data but not WiFi... my wifi can support video streaming... so it is not connection issue.