MacBook Pro download speed lower when external monitor plugged in. iOS devices are not.
Last night, I called my ISP (Spectrum) about slow download speeds on my MacBook Pro (mid-2015, 2.8 i7, 16gb ram, AMD Radeon R9 M370X 2gb, Iris Pro 1536mb), which I normally use with the lid closed and an external monitor (LG Ultra HD at 3840x2160). I reset the modem, then unplugged it and reset it again. The download speed was around 1mbps down and 5mbps up while I was chatting with them. I unplugged the monitor and opened the laptop and the speed went to 5mbps down and 5mbps up.
Then I checked my iPhone SE 2 and it was 73.4 down and 11.8 up. So I checked my iPad Pro and it was about the same. This morning I checked my Apple TV 4k and it was 73.5 down and 11.8 up.
The Spectrum guy is now here looking at the connections outside but I'm wondering if he will be able to do anything if the problem is some devices but not others.
