can't install httpuv on AWS EC2 Ubuntu instance (for Shiny)

Question

I'm following the many online tutorials for setting up a Shiny server using AWS. I created a free tier EC2 instance with Ubuntu 20.04 (64-bit), and I've installed R 3.6.3.

I can't install the httpuv package, which is a dependency of shiny. (Other packages, such as dplyr, work just fine.) This gist shows the output I see when I try to install httpuv; it's extremely long, and unfortunately the beginning of the output is cut off. Before terminating, it sat at line 1205 for hours with no movement.

I'm not the first user to encounter this problem. This RStudio community post from just a week ago looks like the same thing I'm experiencing. This SO question has some suspiciously similar warning messages, but in that case the user solved the problem by re-installing R. I have a brand-new R installation, so that solution doesn't help me. One of the comments mentions encountering problems with limited memory on AWS and suggests installing from source; I get the same output. I've also tried using a larger EC2 instance (30 GiB) and an older Ubuntu version (16.04); no difference.

This GitHub issue also involves httpuv, but the output seems to be different and the problem may have been specific to Raspberry Pi. The first post in this issue mentions that it takes a long time to install httpuv, but installation didn't actually fail.