@lkakas Realy not sure then. Could be a faulty unit i guess but you will need to raise this with TPLink direct. One of their team will reply to you im sure in a day or so.

@ZoloNN I have found that the controller only reports clients that have had any kind of IP triffic hitting the gateway in the last 10 mins or so If a device is quietly sitting there not doing...

@lkakas Do you have a spare, dumb unmanaged switch? Would be curious to see what happens if you put a switch in the middle Modem > switch > ER8411 WAN

@lkakas Do you have IPS / IDS turned on, or any firewall ACLs that control traffic in or out of the WAN connection that may be interfering ? Other than one very specific WAN port bug (reported and...

@Julian2111 Some IDS/IPS options use much more CPU horsepower than others - do you have every option turned on ?

@lkakas If it was me facing this, i would now start enabling other ports as WAN and trying to connect on say WAN/LAN 5 instead and see what happens. I know you say you have checked the cable, can you...