When I discovered clients cannot connect to wifi, I connected with manually configured IP adress and rolled back to 7.0.3. I thought that fixed it for the time being - but now I am not 100% certain it did… Unfortunatelly I did not disable automatic updates and the next time I checked I found my Omnia running 7.1 or 7.1.1 again.
Rolling back to 7.0.3 for the second time did not fix this connectivity or dhcp issue for sure
Rolling back to 7.0.2 just now does not fix it either 
Not sure what to do now. Should this page list static DHCP leases? That’s what I use for most machines.
edit: apologies, dhcp in 7.0.2 actually works again and hands out addresses. I just had to wait a little longer