THE Linnets cost Hitchin manager Darren Salton his job – with former Linnet Darran Hay the new boss.
Salton was sacked immediately after the match.
Hay, whose goal sealed Lynn's Southern League Cup final triumph over Bedford in 2004/05, had been signed for Lynn from Hitchin.
Linnets boss Keith Webb said: "I was only talking to their manager before the game and he was reasonably happy as they'd only lost three games in the league.
"You don't like to see a manager get sacked at any level of the game, but that's the nature of the business."
On his side's win, Webb said: "That's two games now that we've scored in the first ten minutes and all of the Reserve players did very well.
"John Turner and Mark Heath-Preston caused Hitchin problems with their pace and workrate.
"Charlie Defty and Dean Miller were solid at the back, while Rob Murray also deserves a lot of credit in goal.
"He has been travelling everywhere with the team and helping Scott Howie and has had to be patient for a chance. He epitomises the squad."
The Linnets side, mainly made up of Reserves, eased through on Tuesday.
Within 20 seconds John Turner, with his back to goal, netted a stunning overhead kick from a Steve Spriggs cross to score one of the fastest goals seen at The Walks and wake up Lynn's smallest crowd of the season settling down to watch the cup tie.
On 17 minutes Dan Buhlemann burst through the away defence and fired over from the edge of the box.
Hitchin skipper Ryan Frater took a long run-up at a 25-yard free-kick, blasted it and forced a good low save from the assured Rob Murray.
Midway in the half Spriggs cut in but was denied by a good block from away keeper Ricky Perks' legs.
Hitchin's David Iwediuno headed goalwards, but Stephen Harvey "kneed" the ball off the line.
Lynn doubled the advantage with a good move from Murray's kick that saw Spriggs slide in to beat the despairing dive of Perks.
Canaries defender David Deeney was sent off on 39 minutes for two yellow cards, first fouling Joe Francis, then pushing him.
Harvey tried his luck from 20 yards and Perks tipped the shot around the post.
The visitors pulled one back six minutes into the second half as sub Tyron Sealey earned a corner which Shane Hill took and Lance Gentle-King scrambled home.
But on 53 minutes with Hitchin looking for offside, Dean Miller put a ball through to Mark Heath-Preston, who was left to blast the ball into the top of the net and give Lynn some breathing space.
In the closing moments Heath-Preston fired into the side-netting.
Under Salton, Hitchin won the errea Cup in 2005/06, but he and they will have to try again.
Lynn: Murray, Buhlemann, Lake, C. Defty (Spittlehouse* 89), Miller, Harvey, Spriggs, Keegan*, Turner (Vincent* 80), Heath-Preston, Francis (Nicholls* 62). Subs not used: McNally. *= Making first team debuts.
Hitchin: Perks, Deeney, Duckett, Frater, Gentle-KIng, Childs (Mountford 74), Olaleye, Hill, Jackman (Sealey h-t), Iwediuno (Pringle h-t), Mills. Not used: Simpson
Stats, Lynn first, shots on target 5, 6; off target 5, 4; corners 2, 4; offside 2, 2;
Free kicks 11, 9.
Att: 336. Referee: W. Porter (Lincs).