blockchain other nodes are not receiving the mined block

i am taking an online blockchain course and the code runs normal for him but its not on my side ,blockchain nodes are connected with each other when using postman but when i mine a block only one node is receiving the mined block.

i tried running it again, make the algorithm harder to take longer time, changed the ports, made sure that the nodes where connected but nothing worked, i am trying to make an lms system with blockchain as a dataholder, do you recommend to keep doing it and if yes i am little lost and i need help.

here is the code where the problem is

app.get('/mine', function(req,res){
    const lastBlock = blockchain.getLastBlock();
    const previousBlockhash = lastBlock['hash'];
    const currentBlockData = {
        USER: blockchain.pendingUSER,
        index: lastBlock['index'] +1
    };

    const nonce = blockchain.ProofOfWork(previousBlockhash,currentBlockData);
    const blockhash = blockchain.hashBlock(previousBlockhash,currentBlockData,nonce);
    const newblock = blockchain.createBlock(nonce,previousBlockhash,blockhash);
    const request_promises = [];

    blockchain.networkNodes.forEach(networkNodeURL =>{
        const request_Options = {
            uri: networkNodeURL + '/receive-new-block',
            method: 'POST',
            body: {
                newblock:newblock
            },
            json:true
        };

        request_promises.push(request_promise(request_Options));
        
    });
    Promise.all(request_promises)
    .then(data =>{
        res.json({
        note:"new block mined successfully",
        block: newblock
     });
    })
 
});


app.post('/receive-new-block',function(req,res){

    const newblock = req.body.newblock;
    const lastBlock = blockchain.getLastBlock();
    const correct_hash = lastBlock.hash === newblock.previousBlockhash;
    const correct_index = lastBlock['index'] +1 === newblock['index'];

    if(correct_hash && correct_index){
        blockchain.chain.push(newblock);
        res.json({
            note:'new block is added to the chain.',
            newblock:newblock
        });
    }
    else{
        res.json({
            note:'block was rejected',
            newblock:newblock
        })
    }

});

app.post('/USER', function(req,res){
    const newUSER = req.body;
    const blockIndex= blockchain.addUserToPendingUSER(newUSER);
    res.json({note:`USER will be added in block ${blockIndex}.`})
});



app.post('/USER/broadcast',function(req,res){
  

    const newUSER = blockchain.CreateNewUSER(req.body.Academic_id,req.body.Firstname,req.body.Lastname,req.body.birthdate,req.body.academic_year);
    blockchain.addUserToPendingUSER(newUSER);
    const request_promises = [];
    blockchain.networkNodes.forEach(networkNodeURL =>{
        const request_Options = {
            uri: networkNodeURL + '/USER',
            method: 'POST',
            body: newUSER,
            json:true
        };

        request_promises.push(request_promise(request_Options));
    });
    Promise.all(request_promises)
    .then(data=>{
        res.json({note:'user is created and broadcasted to other nodes'})
    });
    
});

even though this function almost works the same it works normal and all nodes do receive the message that is sent to 1 node