@LFNYC I have the exact same issue since moving this device over to AP mode. In the end I have just decided to replace it with a true wireless AP & switch. While the unit seems to function fine in AP mode, it gives me an uneasy feeling that the device clearly is having DHCP issues.

@kyphos Same issues for me. Any fix since 8 months for a permanent issue?

@kyphos Same issue here with C2300. Is there any solution?

@Romantico No, TP-Link told me that they won't fix that issue even if it is under warranty and that I have to purchase another model. Thta's what I did; I purchased an Asus one.

Never go back to TP-Link

@Romantico 

I have devised a solution to using the C2300 as an AP. Not perfect, but functional.

When I started this thread 2 years ago, I was unable to get the C2300 to work properly in "AP Mode".

TP-Link tech support was useless, so I abandoned the effort and deployed an Asus instead.

This week, I needed another AP for a different installation, so I dusted off the C2300 and gave it another go. I'd hoped that in the intervening 2 years, TP-Link might have released a new version of firmware that fixed the defects.  No such luck - the latest version posted on their website for the V1.0 variant of the C2300 is still v2.0.3, dated 20180611.  No updates in nearly three years to fix known, reported bugs. That's abysmal, and is a good reason to avoid TP-Link products.   But I digress.

With the C2300 set for AP Mode, I tried to configure its LAN interface with both "Static IP" and "Smart IP".

Using "Smart IP" is no good.  Their so-called "Smart IP" mode is really "Stupid Broken IP" mode. It uses DHCP to request the LAN parameters from the DHCP server in one's gateway router.  Parameters obtained include the IP address being assigned to the C2300, the subnet mask, the gateway router address and the DNS servers.  When configured for Smart IP, the C2300 does indeed issue a DHCP request, but it continues to do so every 12 seconds. It floods the DHCP server in my gateway router with endless DHCP requests, and fills up its own log with DHCP messages.   Not what one would consider to be a competent implementation.

In Static IP, one can specify the LAN IP address and subnet, but not the address of the gateway router on the LAN. (That's a serious flaw).

Nor the address of the DNS server to be used. The gateway and DNS IPs are required if the C2300 is going to be able to contact the internet to obtain network time (via NTP), or to check on the TP-Link support site for firmware updates.  And worse, when set for Static IP, I found that after a cold restart, it reverts to Smart IP mode (flooding my DHCP server with requests every 12 seconds) even though the configure page still shows it's in Static IP mode.

My 'solution' is to set the C2300 in Router mode, and then manually configure it to function as an AP:

• set the WAN interface to Static, and give it a dummy IP address that is not part of your existing networking plan. I used 10.10.10.10/24

• note that you don't connect any cables to the WAN interface. It's left disconnected. You'll connect the C2300 to your LAN with one of its 4 LAN interfaces.

• set the Default Gateway to 192.168.1.1

• set the DNS to 8.8.8.8 (Google's DNS).

• on the DHCP Server page, turn DHCP off.  <-- this is very important. You don't want the C2300 acting as another DHCP server on your LAN.

• on the LAN page, assign it an IP from your existing subnet. I used 192.168.1.247, subnet 255.255.255.0. Make sure that the address you pick is not within the scope of the DHCP server on your gateway router.

• once you've set the LAN IP, you'll lose connectivity from your PC/Mac to the C2300, since its LAN address has changed from what it started with (192.168.0.1). You have to manually configure your Mac/PC with a static IP in the same subnet (in my case, 192.168.1.1/24). And then reconnect to the C2300 at its new IP (eg 192.168.1.247)  so you can continue with the configuration.

• Set the C2300 time zone to your current time zone. Enable DST if appropriate.

• Optional: In order to obtain network time, the C2300 needs to be able to connect to the internet to (a) resolve the IP of the specified NTP server (such as time.nist.gov or pool.ntp.org), and (b) to connect to the time server and obtain network time. But it doesn't know how to do so. There's no internet connection through the WAN interface.  My workaround was to specify a local NTP server.  My gateway router is a Ubiquity ER-X EdgeRouter and it provides NTP service on my LAN.  So I configured the C2300 to use 192.168.1.249 for NTP. (that's the address of the ER-X). The C2300 then obtains correct time from the ER-X. Any error messages logged to the C2300 syslog get correct time stamps, and the time-of-day access controls also work.

• for good measure, I disabled a bunch of ancillary services in the C2300 that I don't want/need: Printer sharing, Media sharing, Samba, ftp file share, USB sharing, UPnP. All I want it to do is be an Access Point.

Having done all the above, the final step is to configure the wireless settings with the SSIDs, passwords, etc that you want. Instead of Auto for security mode, I specified AES. Some of my iOS devices complained if the radio uses TKIP mode.

For better security, I disabled WPS.

For the 2.4 GHz radio, I specified 802.11n only.  I don't have any old -b or -g devices.  However, I found that the C2300 ignores this setting. According to WiFi Explorer, its 2.4GHz radio still operates in b/g/n mode. 

Having done all the above, connect one of the LAN ports on the C2300 to your LAN. Leave the WAN port disconnected.

My C2300-as-AP has been in service for a few days now with no problems encountered. The only functional limitation is that it's unable to check for new firmware releases from TP-Link since it doesn't know how to connect to the internet.  But it's a moot point: TP-Link hasn't rev'd the firmware for this product since 2018. The likelyhood that there will ever be a new release for it is approx the square root of -1.

I'll be swapping out the C2300 with a proper AP in the near future - one from a company that designs quality products, tests them thoroughly, and stands behind them with firmware releases that fix known problems.