I have received my OpenWrt router, but for some reason, it did not come with a power supply.
Is there a easily obtained substitute that I can use instead?
There are >>1600 different routers supported by OpenWrt, hard to tell which one you refer to…
Going out on a limb, if you are referring to the "OpenWrt One", the answer would be in
USB-C(!) PD(!), 15V(!), >= 2A(!)
all of these conditions must be met, just a USB-C plug alone does not imply either of the other requirements. So make sure that USB-PD, 15V && >=2A are explicitly listed for your power adapter.
Just to be clear, your USB-PD PSU (~charger) must explicitly mention something like:
Type-C: PD3.1 5V/3A, 9V/3A, 12V/3A, 15V/3A, 20V/5A
Only the "Type-C PD" and "15V/3A" (well, 15V/2A) aspects really matters here (the listing I've quoted above are a little better than necessary, but i was just one of the first nice examples I've found).
Alternatively (XOR) you could connect it via (active) PoE according to the IEEE 802.3af/at standards via the 2.5 GBit/s (wan) port.
thanks, I ordered a charger that will output :5V-3A 9V-3A 12V-3A 15V-3A 20V-2.25A 20V-3.25A.
It is a little short on the 20V amperage, however I plugged it in and everything seems to work.