Small Aircraft
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 21.8; Flight Crew Total 2451; Flight Crew Type 1580
Situational Awareness; Troubleshooting; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Other / Unknown
Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification
Staffing; Human Factors
I was enroute on an IFR flight plan. Sometime after passing ZZZZZ intersection on my assigned route and altitude I realized I had not spoken to ATC in a longer period of time than expected. About 18 miles south of ZZZ [VOR]; I received a traffic alert on my ADS-B display of traffic 1;000 feet below; 2 miles. This prompted me to then call to ATC on my assigned frequency. Since I reached no one; and it had been longer than expected I figured they forgot about me and I searched for a frequency to reestablish contact. (I have had ATC miss handoffs occasionally before). I believe it was ZZZ Center I contacted; who then told me to contact ZZZ Approach. I was initially told they were 'too busy for flight following'. I advised them I was on an IFR flight plan. After another attempt or two to have them accept this; my communication with them was established. Several minutes later I was given a telephone number to call after landing; and upon querying why; they just said it was ZZZ Center. I do not know for sure what problem was supposed to be. But I suspect since I received the ADS-B traffic alert; it was a possible loss of separation. When I was somewhere in the vicinity of ZZZZZ intersection; a Controller told all aircraft 'don't call in; I'll call you'. I never received a call from this Controller; and it was only after I did not feel comfortable waiting longer for a call that I then called back to establish contact. I do not believe I missed a call or checking in on a frequency change. ATC was somewhat overwhelmed in spots in this area. I had noticed in my home area flying that some of the frequencies were not staffed  during the COVID pandemic; and I think some of the facilities may have needed to re staff more quickly as traffic began to grow again.
GA pilot reported a loss of communication with the ATC Center resulting in an ADS-B traffic alert.  Reporter cited possible COVID-19 related ATC staffing issues may have contributed to the event.