Air carrier Captain reported loss of the L GPS after departure due to GPS interference and jamming.

Narrative

On departure from ZBAA; at approximately 2000 ft. AGL; we were affected by GPS interference - jamming. We followed all SOPs in accomplishing all checklists in response to EICAS messages; time permitting; during a busy phase of flight. This also included the loss of the L GPS. We further consulted with a bulletin; and accomplished the procedures as required. Following exiting Korean airspace; the L GPS never recovered. Once in oceanic airspace; and beyond VOR/DME reception; the ANP progressively increased beyond RNP 4.0 values. The bulletin was further followed under conditions mentioned; and Dispatch and Maintenance Control were then contacted on SATCOM for further assistance. Maintenance Control had nothing further to offer us for a solution. However; through Dispatch; the Chief Pilot and ATC advised us that we were filed on an RNP 10.0 Oceanic Track. While using all available means to ensure proper navigational tolerance; the EFB GPS display was the most accurate throughout the flight; and indicated us being on course the entire flight. Eventually; the FMC ANP value drifted to over 15.5. Dispatch and Oceanic ATC were notified; and continued flight on current routing was approved; including the current altitude of FL330. Once coasting in near the coast; the DME/DME recalibrated our ANP when within the service volume of the ZZZ VOR. ANP values were then well within the limits to accept and execute the ZZZZZ RNAV Arrival into ZZZ [Airport].The L GPS was written up in a maintenance discrepancy prior to our arrival. No other issues noted.