Can you restart data service with full strength & orange indicator? With some regularity (6-7 times per month) my Android 4.4 phone gets into a data-wedged state where the connection is shown as full-strength LTE, but without connectivity (the icon is orange in the settings drawer). Toggling mobile data and toggling airplane mode do not help, but rebooting the phone does restore service. Sometimes simply leaving it alone will eventually result in data restoration (but that could be a case when it was a transient carrier issue).

Is there some way to kick (restart) the radio or data service to get going again without a reboot? I have root and a terminal, as well as SL4A experience if that would help—I just can't find anything that fits this description in the developer docs. I can't figure out what would be lower-level such that rebooting would cause the needed "kick" but airplane-mode toggle wouldn't.

Note that the apparent answer Restart data connection when stalled? doesn’t actually answer the question, it suggests diagnostics for verifying the connection really is stalled (I don't have any trouble with that part).

(In case it matters, this is a Nexus 5, Android 4.4.3 KTU84M, T-Mobile LTE.)
While I haven't seen that issue, you can restart the radio.

Dial *#*#INFO#*#*, choose Phone info and scroll down.  Click the Turn off radio button, then click its replacement, cunningly called Turn on radio.

A Nexus 5, being Google, should support the standard android_secret_code URIs, so INFO should be present. Other vendors may replace/remove/augment those, so bets are off on anything not directly from Google.