Can I update the firmware for my router using my iPhone or dose the router need to be conected to a computer

Follow your router manufacturer’s instructions. For my Netgear router I have an iPhone app that has a button to update the router, but it has never worked, and neither has the router’s “automatic” update feature. I have to download the update file to my computer, then connect the computer to the router with a cable to install it. YMMV.

Ask the manufacturer of the router.

Just about every router I have ever owned or heard of downloads firmware updates from the internet directly, no other devices are needed

Johnathan Burger wrote:

Just about every router I have ever owned or heard of downloads firmware updates from the internet directly, no other devices are needed

Except my Netgear; when I choose to update it says “no update available, you may be able to download and install it manually.” which I do.

I don't now and never will use a Netgear router.

I have a Google wifi router.

Plugged it in, set it up and haven't messed with it since.

Runs without any issues and automagically updates itself at 2 am when updates are available.

Unless you are a network engineer, you should never have to mess with your router after the initial setup.

It should just work.