airport extreme not allowing more than one wifi device

Excellent .. that gives me exactly the info I need.

Your Zyxel is working as a modem router. But the configuration is screwy.

Notice the unit is handing out addresses in 172.16.1.x but is itself set to 172.16.0.254 which is possible I guess if the airport was behaving as it should but frankly I think it is likely to lead to issues.

It just so happens that 172.16.1.x is reserved for use by the Extreme itself when using guest wireless. Do you happen to have guest wireless turned on?

Even if you don't it is still a reserved IP range in the Extreme.

The old Extreme depending on its age and model may not have had the same problem.

To solve this I think you must change the configuration of the Zyxel.

You could login to the Zyxel and set its LAN to 192.168.1.1 with DHCP range of say 192.168.1.2-254 or smaller depending on how many addresses you need. It can use exactly the same range as it does now but you need to change its IP.

OR

I think it is worth having a go putting the Zyxel into bridge mode.. and testing PPPOE on the airport router. This is trial and error.. It may work fine or might be terrible or not work at all. You will need to know your Earthlink ADSL login username and password.

The instructions to bridge the Zyxel are here. (These might be later model of the same modem or you might have an earlier one again.. the one difference is your modem is set to 172.16.0.254

How to Set the Modem for Bridge Mode for Zyxel P 660R F1

Zyxel P 660R F1 How to Set the Modem for Bridge Mode Alternate

You would need to then reset the Extreme and configure it again to use PPPOE on the WAN interface with your earthlink name and password.

This will be well worth a go.. perhaps you might like to save the configuration of the zyxel before you start in case you get into trouble.

It is possible to somewhat fix the problem using double NAT.. if you ring Apple this is what they will recommend. Around here we don't think it is a good idea.. although it can get you out of trouble if you need things working quickly. Setup the Extreme as a router.. You will get a double NAT warning .. ignore it.. complete the setup.

If you need more help with the Zyxel you should ring Earthlink support.

We can help you for the airport side.

Apple routers can have major problems with DSL.. although your old one worked so the new one should not be all that different.

What is the make and model of the modem?

Is your earthlink modem also a router.. do you use it bridged or in router mode?

What method of authentication is used by your service?

PPPOE is the most common.. IPOE is now used as well. PPPOA is also possible but only with the modem also working as router.

I never was able to use Apple router with PPPOE.

What might be happening is the Apple router is detecting DSL type system and attempting to take over routing which can fail.

If you answer the above questions.. and give us a screenshot of the summary on the airport extreme.. then we can likely figure it out for you.

This is the shot I want.. the popup with the wireless details is not necessary.

6. The Extreme will check the configuration.

Make sure ethernet from modem is plugged into the WAN port on the Extreme.. ie the port nearest the bottom with a circle of circles.

7. Do not create a guest network at this time.. if you need it ask as it will mess things up.

8. I do send the diagnostics to apple because they are useful to me.. I don't really care about Apple using them.

9. Last screen of the setup.. click done and wait for it to finish.. if it says there were problems ignore it.. restart the Extreme.. and open it again in the airport utility.

10. Fix the errors.

We are using double NAT.. it is not a serious error.. ignore it.

Click the error and pick ignore.

11. You should now have a working Extreme and can connect all your devices at once.

If you have any issues following this.. tell me the step and give me a screenshot.

still got the earthlink error message that the ip address was already in use so I'm back where I started

Open the airport in your airport utility.. go to the network tab.. is it set to correctly to DHCP and NAT.. if it is set to bridge just change it directly on that tab.

It will not work properly unless the Extreme is in router mode.. ie DHCP and NAT.

Once you have it in this mode.. it is impossible for the clients to complain about IP being used because they are allocated by the Airport.

first let me say the only reason I'm still using earthlink DSL and their antique DSL modem is that I've been using my earthlink email address for every device, website, service account, online account, utilities, etc for about 20 years . . .

It is time to move on.. the dsl service has woeful speeds cf cable or fibre services from all the other suppliers.. even earthlink maybe can upgrade you to vdsl or some better service.

I realised long ago that using pop mail from ISP was a trap and simply signed up to gmail when it first started.

Create a gmail account..

Sign up to new high speed service.

Keep paying earthlink.. for a few months while you change all your emails over to web mail account (or even apple icloud mail account if you are enamoured of apple).

Honestly it is time to move on after no doubt 20 years of excellent albeit SLOW adsl service.

Some ISP will let you pay a few dollars a month just to use your existing mail accounts. See what earthlink will do for you. You can still access the old email accounts even if you change to another ISP as long as you keep up payment for server access. Your outgoing mails will need to be sent differently so there are some changes to make.. but the pop account can still be used via apple mail or whatever your preferred mail software.

The problem is you don't remember the setup..

maybe I should consider a much better newer dsl modem if they still make them and if it will automatically set up my earthlink account when first connected to my phone jack

A new modem will have to be configured.. unless you buy it from your ISP.. ring up earthlink and ask for price of a new modem.. either preconfigured as router or preconfigured as bridge.. if you go the later.. remember you must also know your adsl login name and password which you have likely never used in 10 years.. so get them renewed at the same time.

at this point I'm even considering finding another old Extreme flat model same as mine that just died because I never had trouble using multiple wifi devices with it other than slow pathetic mbps speeds when more than one device was in use

I don't think this is a solution either.. you still need to configure it.. and you have forgotten the configuration.

I have a feeling your previous Extreme was setup as router..

Using an old one will just have the same slow speeds as before. (although a faster router will not speed up your ADSL internet which is probably slow as).

There is a possibility that the Zyxel you have is setup as 1:1 NAT. This is a special mode that was popular back then.

So to fix the problem for now.. reset the Extreme and do a new configuration.. ignore the automated setup and pick other options.

Here is exactly what I want you to do...

1. Reset the Extreme by pressing the reset for about 10sec until front LED flashes rapidly.

2. In airport utility.. makes no difference if you use iOS or Mac version.. I am doing it from Mac OS.. somewhat better laid out and easier to follow.

Click on the Other WiFi Devices (1) and select the Extreme.. I am using a Time Capsule.. but same thing.

3. This starts the setup wizard.

Choose Other Options in bottom left corner.

4. Choose Create a new network.

5. Go next and fill in names and passwords.. I recommend using short names no spaces and pure alphanumerics.. NOT APPLE AUTOMATED NAMES. Same rules for passwords but can be longer.

to be continued.

Looking at the old setup info..

http://www.dslreports.com/forum/r6952628-Access-Zyxel-645

I am pretty sure you never accessed the Zyxel at any time.. that being the case you used it as I have outlined.

Double NAT in this particular case is no big deal.. due to 1:1 NAT (just means all incoming packets are routed through the modem.. so while not a modem in bridge it is only half a router).

Certainly if you ring Earthlink and talk to them.. they should be able to provide you a much better newer modem.. I hope better than the Zyxel 660 but whatever they have.