Hi ,  @Ltcdata 

Thank you for posting on our business forum.

Below are some preliminary troubleshooting steps we would like to invite you to complete:
1.Could you please run a test by replacing the existing Ethernet cable connecting your EAP to the switch with a shorter one (approximately 1 to 2 meters in length)?
2.Could you please check if you have manually configured the port speed for your switch or EAP? You can access the relevant settings by navigating to Device > Click on Switch/EAP > Manage Device > Ports.
3.Could you please test whether the speed reduction still occurs when your EAP is not adopted by controller?

Please share the results of the troubleshooting steps above with us, and also provide the following information for further analysis:

1.Please confirm whether this issue occurs only on specific EAP devices, or on all of your EAP devices.
2.The complete network topology of your current deployment.
3.Please clarify whether this issue occurred after your EAPs had been running normally for a period of time, or it has existed since the initial deployment.
Thank you very much for your cooperation.

  @Nathan-TP 

Hi!

Thanks for your answer.

To answer your questions:

1: Yes, i did that, with a 1m patchcord directly to the switch. Same issue. Connects at 100mbps.

2: The ports of the switch are all set to default/auto. If i force the port to 1000/full duplex, the AP never establishes link.

3: If i hard reset the ap, the ap boots, it gets adopted, provisioned, and it works and establishes the wired uplink at 1000mbps for a few hours and works perfectly. Then it lowers to 100mbps.

This issue only happens on one 773. The others work perfectly (all same firmware and hardware version, 773(US) V1.0). 

The topology is simple:

Cablemodem --> SG2210MP --> OC200 / 1x650outdoor / 2x265HD / 1x245 / 2x773 (it used to be 5x773's but 3 where moved to another location, and are working ok in that place).

The customer installed the new AP's (the 773's) a few months ago, and i was called to troubleshoot some issues (mostly poor power/channels selection and some location/orientation of the AP's). After a few hours of work, the place had good coverage, roaming, etc.

I noticed a performance issue (low throughput) with this access point in particular. After reconfiguring everything from scratch, this access point only connects at 1 Gbps after a hard reset, and within a few hours it drops to 100 Mbps.

I recommended the customer to put new cables on site (the customer had old cat5), now all the network is done with high quality CAT6.

All the others AP are working perfectly.

Thanks very much for your help.