weak wifi signal and keeps disconnecting

[randi3695]

model hp 250 g4 .

Description: Ubuntu 18.04.3 LTS
Release: 18.04

bcmwl-kernel-source:
  Installed: 6.30.223.271+bdcom-0ubuntu4
  Candidate: 6.30.223.271+bdcom-0ubuntu4
  Version table:
 *** 6.30.223.271+bdcom-0ubuntu4 500
        500 http://al.archive.ubuntu.com/ubuntu bionic/restricted amd64 Packages
        100 /var/lib/dpkg/status

Network controller [0280]: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n [14e4:4365] (rev 01)
 Subsystem: Hewlett-Packard Company BCM43142 802.11b/g/n [103c:804a]
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0, Cache Line Size: 64 bytes
 Interrupt: pin A routed to IRQ 16
 Region 0: Memory at c0500000 (64-bit, non-prefetchable) [size=32K]
 Capabilities: <access denied>
 Kernel driver in use: wl
 Kernel modules: wl

lo no wireless extensions.

wlp4s0 IEEE 802.11 ESSID:"Error"
          Mode:Managed Frequency:2.412 GHz Access Point: 5C:35:3B:A8:BF:02
          Retry short limit:7 RTS thr:off Fragment thr:off
          Power Management:off

enp2s0 no wireless extensions.

i have uninnstalled and try to install again but the same problem. i have modified my country code REGDOMAIN=+4120+01950 but the same weak signal of wifi . i have blacklist brcm80211 and bcma but no results.

can you check please .
thank you.
Erand

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: bcmwl-kernel-source 6.30.223.271+bdcom-0ubuntu4
ProcVersionSignature: Ubuntu 4.15.0-65.74-generic 4.15.18
Uname: Linux 4.15.0-65-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.9-0ubuntu7.7
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Oct 8 21:17:17 2019
InstallationDate: Installed on 2019-10-06 (2 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: bcmwl
UpgradeStatus: No upgrade log present (probably fresh install)