How to address timeout issue on fetch function

Question

I am currently developing a program that utilizes long polling to perform periodic fetches.

However, I am frequently encountering timeout errors during the fetch process, despite having a stable internet connection. I have thoroughly verified that my internet connection is functioning properly, and the issue persists.

I have already tried the following solutions, but the problem still persists:

• increase timeout by signal: AbortSignal.timeout(1000 * 200)
• use keepAlive option
• increase timeout from query string on telegram api
• fetch per 2 second instead of miliseconds

Here are some additional details that may be relevant:

Test by speedtest:

Idle Latency:    20.14 ms   (jitter: 2.87ms, low: 19.27ms, high: 29.80ms)
    Download:     9.76 Mbps (data used: 11.5 MB)                                                   
                522.78 ms   (jitter: 88.34ms, low: 45.85ms, high: 1349.79ms)
      Upload:     0.34 Mbps (data used: 597.3 kB)                                                   
               2274.00 ms   (jitter: 93.18ms, low: 186.00ms, high: 3920.09ms)
 Packet Loss:     0.0%

Error log (actually it happens more than three times):

TypeError: fetch failed
    at node:internal/deps/undici/undici:12443:11
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async handler (/home/user/control-center/start-service.js:15:22) {
  cause: AggregateError [ETIMEDOUT]: 
      at internalConnectMultiple (node:net:1116:18)
      at internalConnectMultiple (node:net:1184:5)
      at Timeout.internalConnectMultipleTimeout (node:net:1707:5)
      at listOnTimeout (node:internal/timers:575:11)
      at process.processTimers (node:internal/timers:514:7) {
    code: 'ETIMEDOUT',
    [errors]: [ [Error], [Error] ]
  }
}
TypeError: fetch failed
    at node:internal/deps/undici/undici:12443:11
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async handler (/home/user/control-center/start-service.js:15:22) {
  cause: AggregateError [ETIMEDOUT]: 
      at internalConnectMultiple (node:net:1116:18)
      at internalConnectMultiple (node:net:1184:5)
      at Timeout.internalConnectMultipleTimeout (node:net:1707:5)
      at listOnTimeout (node:internal/timers:575:11)
      at process.processTimers (node:internal/timers:514:7) {
    code: 'ETIMEDOUT',
    [errors]: [ [Error], [Error] ]
  }
}
TypeError: fetch failed
    at node:internal/deps/undici/undici:12443:11
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async handler (/home/user/control-center/start-service.js:15:22) {
  cause: AggregateError [ETIMEDOUT]: 
      at internalConnectMultiple (node:net:1116:18)
      at internalConnectMultiple (node:net:1184:5)
      at Timeout.internalConnectMultipleTimeout (node:net:1707:5)
      at listOnTimeout (node:internal/timers:575:11)
      at process.processTimers (node:internal/timers:514:7) {
    code: 'ETIMEDOUT',
    [errors]: [ [Error], [Error] ]
  }
}

The snippet code:

const param = `timeout=150&offset=${last_update}`;
const response = await fetch(`${process.env.BASE_URL}/getUpdates?${param}`, { keepalive: true }).then(res => res.json())

full code availabe on github repository