I just got my One S S4 from T-Mobile just 2 days and I rooted it the same day, however right after I unlocked the bootloader, I started getting no signal. I didn't mind and I continued to follow through with the rooting process, and I successfully got root, and then flashed Trickdroid 8.1 and I noticed the same thing.
I couldn't connect to wifi. It would detect the network and I'd put my password for wifi in but it wouldn't connect.
And also, I was getting no signal but I had 4G on..? So basically I could surf the web, and the apps could use mobile data, but I couldn't make calls or send/receive texts. Weird. And this frightened to me because I had just gotten the phone a few hours ago, and so I unrooted and went back to stock.
I would also like help on this issue, as I'm planning to root again, and use a custom ROM. But I would like to know if wifi or signal has any issues