answered
2014-06-23 11:33:33 +0200
Having the GSM antenna ribbon cable changed by technical support service center has solved this problem in my case.
Use a decent non-Jolla device for comparison of coverage performance.
While on same provider or using same SIM card, try loading an identical web page on both devices with prefer 3G enabled.
If the other device does not display erratically behavior and stays stable on 3G while Jolla demonstrates switching between low 3G and slow loading 2G, describe the issue to Jolla tech support.