How to troubleshoot socket hangup in Node app - node.js

Question

So, I have a node app running in 2 servers. When a call is made to the app from either a browser or Postman, a load-balancer will direct the call to one of these 2 servers. I did not setup the load-balancer, so I don't currently have knowledge of how exactly it is set up.
The Node app, basically, will get a call with some data, pull a profile from Redis, then send the required data to Google Analytics. It will then return a 1x1 pixel gif back as a response, if successful, and a 400 status and a message if there is something wrong with the call like missing data or the profile key doesn't exist in Redis. I'm using Express to handle the calls and I'm using the Redis module to handle communication between the app and Redis.
Intermittently, we are seeing failed calls (no response) in the browser (Chrome and Firefox), but they will succeed in Postman. When the calls fail in the browser, I'm able to see all my logs from the app and no errors. The hits are also sometimes going to GA as we expect them to.
On occasion, I can see a failed call in Postman and the error says 'socket hang up'.
My question, really, is where should I look to find whats causing this? I'm not a network guy, and I'm kinda stumped on this.
I checked to make sure that my responses are closed correctly. I'm
using res.send() on all of my calls.
I've tested the app locally with postman and a
browser, with no issues.
I have my timeout in Postman set to 0 for
infinite, I have ssl verification turned off and I'm not using a
proxy.
I have no errors popping up in my app
We also have a ruby app that this one is replacing that does not exhibit these behaviors and I'm not sure if that's due to Ruby handling things differently than Express, or my bad programming.
Is it possible that communication between the app and Redis is getting slow and causing the socket hang up error? Or do anyone think this is more of anetworking issue?
I'm obviously not expecting anyone to be able solve this issue for me, I'm really just trying to learn and find out where I need to be looking to find out whats causing these issues.
Here is an example of one of the calls I'm making in case I'm messing this all up in the way I'm handling calls:
How I'm setting up my Redis connection:
var redis = require('redis');
var client = redis.createClient();
const { promisify } = require('util');
const hgetallAsync = promisify(client.hgetall).bind(client);
const hsetAsync = promisify(client.hmset).bind(client);
const existsAsync = promisify(client.exists).bind(client);
const deleteAsync = promisify(client.del).bind(client);
And how I'm using these to makes calls. This is a bit convoluted, but the reason is because the redis module makes Async calls and I was trying to get them to work "synchronously":
/**
* Record a pageview in GA
*
* #var {bool} exists - This returns a value of 1 if the profile exists in Redis and 0 if it does not
* #var {*} getall - This returns the profile, from Redis associated with the profile id
* #var {*} reqobj - Contains referrer, user_language, and user_agent
* #var {*} params - This is the query string from the url. Example query string: ?a=1&b=2&c=3
* #var {array} pageViewArray - [profile_id, pageView]
*/
router.get('/example.gif', function (req, res, next) {
var clientId = Before(req, res);
if (DatasetCheck(req, res)) {
var profileId = GetProfileIdFromCookie(req);
var json = {};
var params = req.query;
if (profileId) {
var exists = existsAsync(profileId);
var getall = hgetallAsync(profileId);
var validate = validation.ValidExampleRequest(clientId, req.query);
if (validate == true) {
var reqobj = RequestEnvironment(req);
var mergedobj = { ...reqobj, ...params };
var pageViewArray = PageView(mergedobj);
if (pageViewArray != false) {
exists.then(function (exists) {
if (exists > 0) {
getall.then(async function (getall) {
reqobj = RequestEnvironment(req);
var mergedobj = { ...reqobj, ...params };
PageViewPart2(mergedobj, getall, pageArray[1]);
}).then(function () {
//res.send(result);
RespondWithPixel(res);
});
} else {
logger.error("get example.gif ==> Profile does not exist");
json.status = "get example.gif ==> Profile does not exist";
res.status(400).send(JSON.stringify(json));
}
});
} else {
logger.error("get example.gif ==> Invalid hit");
json.status = "get example.gif ==> Invalid hit";
res.status(400).send(JSON.stringify(json));
}
} else {
logger.error("get example.gif ==> Invalid hit request");
json.status = "get example.gif ==> called with an empty hostname: " + params.hostname + " or path: " + params.path;
res.status(400).send(JSON.stringify(json));
}
} else {
logger.info("get example.gif ==> profileId is invalid")
json.status = "get example.gif ==> profileId is invalid or missing";
res.status(400).send(JSON.stringify(json));
}
}
});