Problem using TimeMachine with Mac over WiFi

I originally asked this in the wrong subforum. Trying again.

I’ve had a WDMyCloudEX4 running for a number of years, using it from a couple of personal Macs. No Windows machines for us.

It sort of mostly works, though it’s clumsy. But there’s one issue that I’ve always had that I’m finding to be increasingly problematic. Basically, I can only access the thing over a wired connection, not WiFi. That limits flexibility, now that I also want to use it with a newer MacBook Pro that has no physical network connector, (Yes, I could get one, just don’t feel that I should have to.)

I have a Comcast/Xfinity modem with built-in WiFi. The WdMyCloudEX4 connects to the modem with a network cable.

On my older laptop, with a wired connection to the modem, I’ve been mounting as afp://WDMyCloudEX4._afpovertcp._tcp.local, and that mostly works. Not the fastest thing in the world, but it works. (I don’t remember where that mount format came from; what all I had to do to set it up has been lost to history, and I can’t find any reference to that mount format in the documentation.)

But trying to use it over WiFi:

On my new laptop (both are running HighSierra), afp://WDMyCloudEX4._afpovertcp._tcp.local totally fails. No success connecting at all. Following advice I read somewhere else, I found that I can mount most shares using smb://wdmycloudex4 or cifs://wdmycloudex4, but mounted that way, TimeMachine doesn’t recognize the share as compatible.

On my older laptop, (though still High Sierra), if I switch to WiFi, things are about the same as on the newer laptop, but for even that limited access I have to use the explicit IP address, so smb://xxx.xxx.xxx.xxx.

So I can connect to the device, just not in a way that is compatible with TimeMachine.

Oh, yes, and there’s also an iMac using TimeMachine. It’s not normally ported, so always wired. It works OK.

Suggestions, anyone?

OK, now this is bizarre. If I connect as afp://<ipAddress> it seems to working. (Results remain to be seen.)

Why do I need to use ip address here, but other forms are OK with the symbolic name? (e.g. smb://wdmycloudex4)?

Same problem on My Cloud Mirror 2TB and mid-2013 MacBook Air. Everything is as expected on Ethernet with local host name appearing in finder and able to use same for dashboard login, but not on wifi (Google Mesh). I can access by IP address only. Would love to get the answer on this.

And would love to connect to the drive without having to log in each time. Any thoughts on this?