We lost our 3 connection yesterday, think this was a 3 issue. It appears to be up and running again and our Archer MR600 says connected to internet, our devices are also wifi connected to the Tp link, but all say no internet. I removed the SIM card and put it into a mifi and it's working perfectly so it looks like the 3 signal is back fully and stable. I have tried unplugging the router and restarting a couple of times but no help, still everything lights up saying fully connected but wifi connected devices say no internet. I haven't got anything connected via a cable so unsure about that.