XE104 Loses Internet Access When More Than 2 Devices Are Connected

[AZRaptor]

I have been running an XE103 and a couple XE104s in the house for quite a while now without issue, but in the last few weeks I've had an issue where if more than two of the ethernet ports on the XE104 downstairs have active connections the whole unit loses Internet access. If I unplug cables down to to devices the Internet access comes back. I've swapped the XE104 units and they both have the same issue when used downstairs. I thought maybe there was a new source of noise on the powerline, but nothing has really changed in our appliances.

I'd appreciate any suggestions of thing to look at.