How to connect a MacBook Pro with a MacBook Air ?

SlFus1ng wrote:

Connected the 2 computers with a Thunderbolt to USB-C cable. Computers can't see each other. Will try USB to USB-C next.

Do you mean an Apple Thunderbolt 3-to-2 adapter paired with a Thunderbolt 1/2 cable?

If you have the computers connected in that way, and you are trying to use one as a drive for the other, see:

Transfer files between two Mac computers using target disk mode - Apple Support

Transfer files between a Mac with Apple silicon and another Mac - Apple Support

If you are trying to network the Macs, using Thunderbolt as a substitute for Ethernet, see

Use IP over Thunderbolt to connect Mac computers - Apple Support

Set up file sharing on Mac - Apple Support

MacWorld – How to use file sharing on your Mac

A USB-C (DisplayPort) to Mini DisplayPort cable would have connectors that physically fit into the ports on your new MacBook Air and your old MacBook Pro. But such a cable wouldn't carry a Thunderbolt signal. If that's the type of cable you tried, it would explain why the computers "can't see each other."

Since the MacBook Air only has USB-C connections, external drive won't work and thumb drives would take forever....

External drives that have USB interfaces will work just fine. Apple (and others) sell adapters that go from USB-A to USB-C.

USB-C to USB Adapter - Apple

If you have a portable external drive that came with a Micro USB 3.0 B to USB-A cable, you could use an adapter (see above). Or cut out the middleman with something like this:

Amazon Basics USB-C to Micro USB 3.1 Gen 2 Fast Charging Cable, 10Gbps High-Speed, 3 Foot, Black

SlFus1ng wrote:

I want to manually move some files from the old computer to the new one (and vuce versa). My wifi is really slow and iffy.

I take it that iCloud Drive and File Sharing are out, given that your Wi-Fi is "really slow and iffy."

I believe that you can make your new Apple Silicon machine look like an external disk to your old Intel machine. Sounds like a USB-A to USB-C cable would work here. Check that it's one that carries data, not just a charging (only) cable.

Transfer files between a Mac with Apple silicon and another Mac - Apple Support

The reverse (making your old Mac look like an external disk to the new one) may not be possible without buying $80 in specialized Thunderbolt connection hardware. Sounds like Big Sur and later don't support letting an Intel Mac be a USB Target Disk, and don't support pulling data from an Intel Mac acting as a USB Target Disk.

Transfer files between two Mac computers using target disk mode - Apple Support

Of course, you could just get an external drive, USB flash drive, or SDHC/SDXC memory card and use it to carry data from one Mac to the other. (Attaching the drive to one Mac at a time.)

Connect both Macs to the same Wi-Fi network or use a direct Thunderbolt or Ethernet connection for faster transfer. Open Migration Assistant on both Macs (Applications > Utilities > Migration Assistant).

On the MacBook Pro (target Mac), select From a Mac, Time Machine backup, or startup disk and click Continue.

On the MacBook Air (source Mac), select To another Mac and click Continue.

Follow the prompts to select the MacBook Air as the source and the MacBook Pro as the destination.

Define "connect".

What are you trying to accomplish?

Thanks, I will try it!