Why are my Steam downloads so slow on Pop OS?

First, check the units. Steam may show megabytes per second while a speed test reports megabits per second. Eight megabits is roughly one megabyte, so 10 MB/s is about 80 Mbps. Steam also has a setting to display download rates in bits per second if that makes comparison easier.

Run a speed test with Steam paused, then try a regular file download. If those are slow too, look at the connection before changing more Steam settings. If they are consistently faster, the issue may be specific to Steam or the drive.

Since you're on Wi-Fi, check which band you're actually connected to, not just which one is preferred. A 2.4 GHz connection can be slower or more congested than 5 GHz. The router being close doesn't necessarily tell you which band is in use.

If possible, test over Ethernet or closer to the router. That gives you a useful comparison before you start editing network configuration files. A forced 5 GHz setting might help if the network supports it, but check the current connection first.

Take a look at Steam's download settings too. Make sure a bandwidth limit isn't enabled and try a couple of nearby download regions. The closest region isn't always the fastest, though changing it won't help much if the Wi-Fi test is also struggling.

Test with one game downloading at a time so the numbers are easier to compare.

The separate drive is worth checking if the network looks healthy. Steam has to write and unpack game data while downloading, so watch its disk activity alongside the download graph. Try a small download to the internal drive if there's room and compare.

That won't prove the drive is faulty, but it can help narrow down whether the slowdown follows the destination. Also check that the intended drive is mounted where you expect before testing.

Both Steam packages being slow makes a packaging issue less obvious. I'd hold off on more random config edits for now, especially if you're not sure what was changed.

If the connection remains slow outside Steam, identify the actual Wi-Fi adapter and its driver. The command lspci -nnk can show PCI devices and the driver in use. Look for the network controller section rather than the CPU or chipset entries.