B-737 air carrier pilot reported GPS jamming during cruise in domestic airspace. The flight continued to the destination and landed.

Narrative

Approximately 3.5 hours into our ZZZ1-ZZZ Flight we received an ACARS message to contact Dispatch. We received another message to call Dispatch on the crew phone shortly thereafter but we were in the vicinity of a Missile Range and were intermittently losing GPS and WIFI due to jamming. We communicated this to Dispatch via ACARS and attempted to contact Dispatch by Dispatch Direct VHF via ZZZ [Flight Service Station] but were unable to make contact. Dispatch then sent the following message via ACARS CONSIDER LOWER ALTITUDE TO BURN FUEL; INCORRECT MEL INFO APPLIED; CURRENTLY APPROX 3K OVER MAX LANDING." At that moment we were on track to land with the Performance Data planned arrival fuel of 7.8 thousand pounds which would have resulted in a landing weight around 144.6 thousand pounds.We were then patched through to Dispatch from Center and the dispatcher explained that the correct weight penalty was not applied on the Performance Data we departed with. The Performance Data we departed with was a adjusted Performance Data and did state the correct MEL (27-XXX Flight Spoiler Systems) and also stated "TAKEOFF PERF PENALTY APPLIED IAW (In Accordance With) MEL 27-XXX). The dispatcher explained that the takeoff penalty had not been correctly applied because the specific spoiler pair (2/11) was not listed in the Logbook entry. This specific spoiler pair warrants additional weight limitations per the MEL DP (Departure Procedure) procedures. I had reviewed the MEL and briefed the Operator procedures with the FO before flight. I had also looked at the DP procedures and thought that our Performance Data had adequately adjusted our takeoff and landing weights per the MEL.Dispatch advised that we land with 4.8 thousand pounds and select the longest active runway. We calculated a conservative landing distance of 6600 ft and mentioned that we would likely land with more fuel than that to balance our available options in case of go-around etc. We coordinated with Center and Approach Controllers to descend early; take delay vectors; and enter holding. I kept the FAs (Flight Attendants); passengers; and dispatcher informed of our plan and we landed flaps 40; brakes 3 without any issue. FOB at landing showed 5.0 thousand pounds.CauseAfter landing I called the Maintenance Control and Dispatch to discuss the problem. My understanding is that the original MEL entry was not performed correctly. Maintenance Control added the correct spoiler pair note while we were in flight. Dispatch informed me that they only became aware of the issues because the dispatcher I spoke with was planning the next flight for our aircraft and began working the problem backwards to realize that we had departed 12K pounds over the correct MEL weight and were going to land heavier than required by the MEL as well. It is not clear to me if the original dispatcher was ever aware of the mistake. I believe that greater awareness of the major weight penalties of this specific MEL would have prompted me to reach out to maintenance and Dispatch before the flight if the spoiler pair was not listed. The operator procedures of the MEL do not make a note of this however and because the lights are disabled by the maintenance procedure there is no way of seeing which spoilers have been deactivated. During preflight we reviewed the operator procedures; had what we thought was a valid Performance Data that accounted for the MEL; and were aware that we would conduct a landing assessment for ZZZ. Although we resolved this situation without major issues; it did place us in a position of having to very closely manage our fuel burn - if we kept too much fuel we would increase our landing distance unacceptably and if we kept too little we would be using reserves."