I noticed this too. My parents house at kepong used to have 4g before, and usually 2g and 3g are hard to connect there, and I'm quite surpise with the good connection of 4g available. Until three weeks ago, no longer can get the 4g signal anymore.

When I back to my place at selayang, no 4g, and 3g will just connected like 5-10 min, and then disconnected by showing full signal, but unable to make or receive call, and no internet as well.

But these doesn't happend at my office in Cheras. So I guess maybe it's coverage problem.

Filed a report and talk to customer service, he suggest me to restart phone.. troubleshoot etc, nothing works. Trying the celcom3gmcc apn now, let's see will it get better...