Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Communication Breakdown
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification
Staffing; Procedure; Human Factors
On arrival into EWR one frequency was running what is usually 3 or 4. 128.55 was running all arrivals for all sectors and the departures from EWR. Frequency congestion was high and many aircraft were missing calls. We were at 8000 ft. on the PHILBO THREE having just passed DYLIN. Given instructions to descend to 4000ft. Pilot Monitoring read it back as 4000ft; I set it and verified altitude selected and started a decent. I happened to glance at the TCAS and the line of aircraft compared to my altitude were all leveled at 5000 ft. I stopped descent at 5000 and when able to get a word in queried to confirm 5000 for us. He responded yes; thank you. The rest of the arrival had additional issues including a late intercept to final and being left at 4000. Having other traffic not complying with instructions of ATC and being told to maintain 4000 after starting a decent after being told cleared the approach. We were able to stop at 3700. We were out of position for an ILS but I said I could accept a visual if we got it immediately and I could descend to keep clear of clouds. We were cleared the visual. After landing; I asked for feedback to be relayed from Ground to Approach and was given a number to call to relay my concerns TRACON supervisor answered the phone. I believe that due to frequency congestion we were either given a wrong altitude or read back the incorrect number. As both the Pilot Monitoring and I heard the same number; read it back and were not corrected; I think it was the former. I really feel the overall threats were driven by the lack of multiple controllers. The controller was overloaded.
Captain reported receiving the wrong altitude for a descent clearance during vectors for the approach into EWR.