Using migration assistant

Buy yourself a good quality EHD to use TM on. Most experienced users here recommend the OWC Mercury Elite Pro. After you have migrated you can use it for the new Mac's TM drive which makes it a very smart investment. '

Backup the 2011 with TM this drive, connect it to the new Mac and then launch MA and follow the on-screen prompts and it will be done. Normally takes 2-4 hours depending on the amount of data migrated.

As stated, very very simple to do and dead reliable.

Hello, Mikeroe.

It's called "beachballing" - that revolving colour wheel thingy.

You probably did nothing wrong. Migrating data can take a very long time 10-12 hours or more.

It depends on the amount of data being transferred, the drive connection (USB vs USB-C vs. ethernet, for ex.)

Are you doing a Mac to Mac migration or using Time Machine backup drive?

Do you recall how much data was estimated for your migration?

When you buy a new Mac the easiest, quickest and most reliable method to migrate from the old Mac to the new Mac is to simply connect the old Mac's Time Machine External Hard Disk to the new Mac using a USB cable before you turn on the new Mac. You will likely need a USB A to USB C adapter, you can find them on Amazon for $10 or less. When you start the new Mac for the first time it will startup Setup Assistant (SA), SA will get to a point where it asks if you are migrating from another computer, select Yes  and follow the on-screen prompts and it's done! It is THAT simple.

If you have already done SA on the new computer then simply connect the Time Machine External Hard Disk using a USB cable and launch Migration Assistant (MA) which is located in Applications - Utilities - MA. Then follow the on-screen prompts. 

The ONLY difference between MA and SA is MA will create a new user account that you need to log into.

Both SA and MA migrate applications (not 32 bit apps), data files & settings. They do not migrate Mac OS itself. Some professional apps such as Adobe and Microsoft apps may require re-installing their apps as they will not allow them to be migrated. As long as you kept the security keys for installing their apps, it is not an issue. 

Finally, please NEVER EVER use WI-FI to migrate, this will fail in almost 100% of the situations in my experience. WI-FI was never intended to move large amounts of data at one time.

This is for the MacBook pro, but same idea:

Transfer using Ethernet. To transfer your data over Ethernet, use an adapter (available separately) to connect the Ethernet cable to your MacBook Pro. Connect the other end of the Ethernet cable to your other computer (you might need another adapter, if your computer doesn’t have an Ethernet port). Before transferring your data using Ethernet, make sure your MacBook Pro battery is fully charged.

And Wifi is extremely unreliable for this. The other options DI Johnson listed are much better.

Do you have ethernet on the M1?

(There will be a connection on the power supply)