Light aircraft pilot reported loss of GPS signal in the vicinity of CKB.

Narrative

While enroute IFR from ZZZ to CKB (Clarksburg; WV); I experienced intermittent complete loss of GPS signal across all onboard systems--including a Garmin 430W (IFR GPS); a GI 275 with integrated VFR GPS; and a Stratus 3 connected to ForeFlight. The issue began approximately 40 NM west of CKB and persisted through descent; ultimately resolving about 20 NM east of the airport.The outages lasted from several seconds to several minutes and occurred randomly during cruise; climb; and descent. There were no RAIM (Receiver Autonomous Integrity Monitoring) or antenna failure alerts; but the Stratus/iPad track showed discontinuities and occasional erroneous drops to ground level. At the same time; ADS-B traffic warnings were unavailable; and the system generated spurious terrain alerts. The flight was conducted in VMC at ~7500 feet MSL; well above terrain.The issue was first identified when the position indicator and magenta line disappeared from the 430W and I got multiple failure warning alerts on the 430w. Cross-checking with the GI 275 and iPad revealed all systems were affected; indicating an external source rather than internal malfunction. The 430W continued to function for ILS guidance; and communications remained unaffected.Upon discovering the problem; I reported the GPS loss to Clarksburg Approach. I originally intended to fly the RNAV approach to Runway 21 at CKB; but due to the unreliability of GPS; I requested and was assigned vectors to the ILS 21 approach instead. This action was necessary because both the Clarksburg and Morgantown VORs were NOTAMed out of service; leaving no viable radio-based alternatives to establish on course without ATC assistance.The loss of GPS and simultaneous VOR outages significantly impacted navigation options and increased reliance on ATC vectoring. The situation resolved abruptly east of Clarksburg; and all systems returned to normal for the remainder of the flight; including the leg to ZZZ1.My assessment is that contributing factors likely include external RF interference or GPS jamming; which is known to occur in this region. No avionics work had been done during the recent annual inspection; and no onboard electronics appeared to contribute. Human performance was appropriate--I identified and mitigated the issue promptly; requested a suitable alternate approach; and maintained situational awareness throughout.