Welling suffered a surprise 2-0 defeat to mid-table Weston-super-Mare in Blue Square Bet South on Saturday.
The Wings made the long trip to the Woodspring Stadium on the back of four straight wins in the league.
But Jamie Day's side found themselves two goals down with just 20 minutes gone, thanks to a brace for the Seagulls' Marcus Duharty.
Loui Fazakerley and Andy Pugh saw early opportunities saved for Welling, before Weston scored twice against the run of play.
Duharty’s double strike, the first from close range and the second a header, left Welling with an uphill struggle.
The visitors continued to control the game, despite falling behind, with Pugh, on two occasions, and Cumbers going close to reducing the deficit.
Kane Ingram hit the bar for the home side after the break while, at the other end, Cumbers (pictured) was denied by a good save by keeper Lloyd Irish.
As Welling pushed forward, gaps started to appear at the back but Weston were unable to add to their tally.