Rogue wireless device. Block not working

[DrEggman]

I have 2 x GT-BE98s, and they were all working fine. They have an ethernet backhaul.

Recently I have been having several problems. The ethernet backhaul has down rated itself from 10gbps to 100mbps, and nothing will improve it. I have tried new cables etc. Also, another ethernet link to another switch upstairs will now only work at 100mbps too, even though it is a gigabit device and in the 10gbps socket. It was working fine until a month or so ago. Is there a problem with the 10gig sockets?

Also, randomly the wireless will drop out. I have seen another post on here similar, but not the same. The devices stay connected, but it is as though the router is blocking the DNS requests, as all devices say no internet, but can access local devices. 

Finally, I have a problem with a WiFi device Auth and Deauthing several times every second. I don't know the device. The MAC address corresponds to Tuya Smart Inc, from whom I have a couple of smart plugs, but these are already connected, and have different addresses. The problem still exhibits when these are turned off too. 

I have added the MAC address to the block list, but this seemingly doesn't stop it from doing it. I have changed the WiFi name and password, but it is back again. Does it need the correct password to attempt this? I have attached a snippet of the log below. It seems to be doing it several times a second, 24 hours a day. No wonder my router keeps restarting, and having problems. Any ideas?

Dec 20 22:11:08 wlceventd: wlceventd_proc_event(685): wl3: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3.2: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3.2: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3.1: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3.1: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3.2: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3.2: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3.1: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(645): wl3.1: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:09 wlceventd: wlceventd_proc_event(685): wl3: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(645): wl3: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(685): wl3.2: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(645): wl3.2: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(685): wl3.1: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(645): wl3.1: Deauth_ind 7C:F6:66:29:3B:69, status: 0, reason: Unspecified reason (1), rssi:0

Dec 20 22:11:10 wlceventd: wlceventd_proc_event(685): wl3: Auth 7C:F6:66:29:3B:69, status: Successful (0), rssi:0