I have the same issue with my KS800 series as well. It works perfectly right off the box. After the first firmware upgrade it causes the "invalid ip addresss, cant connect to internet" after sitting on the phone with Tech Support didnt work out. They sent a technician out to replace wifi network module (v1165).
Few days earlier, my TV got a new version update v1168.3. The wifi stop working again, same issue. Time to call the techinician out again.
Having the same issue again. It's exhausting and so frustrating. So far I have had only bad experiences with Samsung products and customer service. What number did you call to have the technician come out? I'm tired of trying to fix this on my own.
My WIFI was bullet proof for many months, then some problems connecting became common. I finally rebooted the TV via system/support/reset in the TV's menu selection, and it seems to have solved the problem. If this were to fail then reseting the Smart features would have been my next course of action.
If the software is up-to date, you have completed a factory reset on the TV, have reset the router, have contacted the service provider and you still cannot connect to the internet; then we would recommend having a technician look at the unit.