Poor to Non-existent Wi/fi on MAC book 13" 2017 model

[nevw]

I have MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports)
Mac-OS Big SUR 11.1 520 SSD HD 16 GB RAM.

I have a Very poor and persistant Internet speed when using Wi/fi or occasionally Ethernet Cable.
I have a NBN connection with Fibre to the House.
Download speed in 27MB/sec. (I have a 25mb/sec Connection)
COnnection has been checked and a new modem fitted. No improvement.
I have had the logic (main) board replaced. a clean reinstall of software.
Wi-fi antennae replaced.
The speed on Wifi is pathetic to a point where there are more page errors than good loads. Too long to Load, page not found
When a page does load it is very slow.

Speed test OK

Have tried in Safe mode,
in Normal mode with only the bacic applications running no change still slow.
Connect the ethernet cable no change, turn off Wifi Speed is there on the ethernet. After a while it will slow down, may take hours or sometime a day or 3

Now to make matters worse or something my IPAd using the same Wifi Modem /network is not affected .

QUestion: What is going on, what is possible cause and cure
TIA

 

[Cory Cooper]

Hello and welcome.

-How does the Wi-Fi work with the MBP in other locations?
-Do you have any third-party utilizes or antivirus installed and running?
-Is the firewall enabled in System Preferences... > Security?
-Did you customize the Network > Wi-Fi settings at all?
-Have you tried power cycling the router?

C

 

[nevw]

Cory,
I have have total AV anti virus And no difference if running or not.
Firewall is enabled
No customisation of Network settings or Wi-FI
Power cycling the Router gives good WI-FI speed for about an Hour sometimes less. sometimes no improvement at all, We have tried different routers. the provider had supplied 2 new routers and no improvement. The problem is somewhere in the MBP.
Wi-fi on the Ipad or Iphone is good in all places in the house
If MBP is in other locations in the house the speed is lousy. Ipad good anywhere