Allow Anonymous Access

Can you try with "NAS-NAME\Username" instead of just username ?

Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed. Disconnect all previous connections to the server or shared resource and try again.

This means precisely what it says. Windows will not allow you to connect to the same server using two different usernames at the same time. This is a trick that gets you two user names - if you use the IP address for one logon, you can use the nasname for a second one. That's because Windows doesn't know they are the same machine. That is why \\hostname fails, and \\ipaddress works in your case - you have simply run across that trick.

Check the credentials manager in the the control panel, and either edit the credentials to use the appropriate user name, or just delete them.

Removing the 'Allow Anonymous Access' box seems to also stop uses from accessing the folding using the Readynas Remote App on my Android phone.
I can login but when selecting a shared folder with out the 'Allow Anonymous Access' box tick I do not get access

ReadyNAS remote needs rights to be configured directly on the website https://readycloud.netgear.com/ . On my NAS rights for cloud users are greyed out, I believe that for those users they are greyed out too on yours and haven't read or write ticked.

I am not sure where this changes are to be make in that site.
But if you are meaning on the access tab and right click on the shared folder??
The setting are set to everyone - read/writes access

I as also having trouble access it on my windows PC.

but I can access the files and folder though
https://readycloud.netgear.com
https://readydrop.netgear.com/

websites

try to go to https://readycloud.netgear.com/, login with your netgear account (the one that configured the NAS) then go to manage, select your NAS if needed. Then you should see your NAS and all the shares appearing, you can set rights by right clicking on those shares. That said the allow everyone should be enough.
You can also check that on your device admin page, category cloud, the users mentionned are properly listed in the readynas remote users.

Yes all of this is correct.

as I say using the web interface I can access these folders and files but not on the phone or with the PC app

What happens if I un-install or remove the readycloud I do not belive i need that option any way as I use a DDclient and on myself the admin need to access the files this way. and not very often. ?

Also the everyone option in the readycloud and on the NAS box. can someone confirm this is not an anonymous login and the person need a user account ?