Apple Watch Ultra 2 connection very slow when connected to iPhone
Recently set up an Apple Watch Ultra 2 running watchOS 10.0.1 paired with an iPhone 14 Pro running 17.0.1. When the watch connects through the phone, speed tests show it's downloading at about 2 or 3 Mbps max and won't download music when charging because it says the connection is too slow. But if I turn off the phone and the watch connects directly with wifi, speed tests indicate a connection around 45 Mbps.
Why is the watch's connection uselessly slow through the iPhone but much faster with a direct wifi connection? Is there anything to fix this? I've restarted both devices but that's had no effect.
Apple Watch Ultra 2, watchOS 10