2020 iMac Wi-Fi speed dropped after updating to Tahoe 26.2

Hi Luis. Many thanks for your kind response, much appreciated for your time in helping me.

I do not run any VPN software. I barely download anything from online except a few stuff long in the past. I prefer stability therefore, I don't use any movies or music or graphics or videos or any graphic stuff on my imac. Nothing downloaded except pre installed apps which also I rarely use.

I tested in normal mode (55-65mbps), then safe mode was same, and back again in normal mode was same 55-65mbps at this time.

So it remains slow. My other older 2012 imac is on Catalina and still at 170-180 mbps. While iphone is 506 mbps.

I deleted some google updater files that were idle just now.

Please suggest any tips on how I could fix this matter? Many million thanks again.

I could not find any unsigned files to delete, perhaps you could guide me, if that is helpful to increase the wifi speed.

Here is the Etre report:

EtreCheckPro version: 6.8.12 (68084)

Report generated: 2026-01-19 23:03:47

Download EtreCheckPro from https://etrecheck.com

Runtime: 3:06

Performance: Excellent

Problem: Computer is too slow

Description:

Wifi is slow on this iMac, 2020. After Tahoe 26.2 upgrade yesterday at

50-60 mbps. Imac 2012 is faster at 120-150 mbps with Catalina. iPhone

is perfect showing 500 mbps.

Major Issues: None

Minor Issues:

    These issues do not need immediate attention but they may indicate future problems or opportunities for improvement.

    No Time Machine backup - Time Machine backup not found.

    Heavy RAM usage - Apps are using a large amount of RAM.

    Apps crashing - There have been numerous app crashes.

    Apps with heavy CPU usage - There have been numerous cases of apps with heavy CPU usage.

    Unsigned files - There are unsigned software files installed. These files could be old, incompatible, and cause problems. They should be reviewed.

Hardware Information:

    iMac (Retina 5K, 27-inch, 2020)

        Status: Supported

    iMac Model: iMac20,1

    3.8 GHz 8-Core Intel Core i7 (i7-10700K) CPU: 8-core

    32 GB RAM - Upgradeable

Video Information:

    AMD Radeon Pro 5500 XT - VRAM: 8 GB

        iMac (built-in) 5120 x 2880

Drives:

    disk0 - APPLE SSD AP0512N 500.28 GB (Solid State - TRIM: Yes)

    Internal PCI-Express 8.0 GT/s x4 NVM Express

    S.M.A.R.T. Details: 1% used, 39.72 TB written, 100% health, 174 unsafe shutdowns

        disk0s1 - EFI [EFI] 315 MB

        disk0s2 [APFS Container] 499.96 GB

            disk1 [APFS Virtual drive] 499.96 GB (Shared by 6 volumes)

                disk1s1 (APFS) [APFS Container] (12.26 GB used)

                    disk1s1s1 - Macintosh HD (APFS) [APFS Snapshot] (12.26 GB used)

                disk1s2 - Macintosh HD - Data (APFS) [APFS Virtual drive] (271.01 GB used)

                disk1s3 - Preboot (APFS) [APFS Preboot] (2.74 GB used)

                disk1s4 - Recovery (APFS) [Recovery] (1.45 GB used)

                disk1s5 - VM (APFS) [APFS VM] (20 KB used)

                disk1s6 - Update (APFS) (6 MB used)

Mounted Volumes:

    disk1s1s1 - Macintosh HD [APFS Snapshot]

        Filesystem: APFS

        Mount point: /

        Read-only: Yes

        Used: 12.26 GB

        Shared values

            Size: 499.96 GB

            Free: 212.34 GB

            Available: 222.50 GB

    disk1s2 - Macintosh HD - Data [APFS Virtual drive]

        Filesystem: APFS

        Mount point: /System/Volumes/Data

        Encrypted

        Used: 271.01 GB

        Shared values

            Size: 499.96 GB

            Free: 212.34 GB

            Available: 222.50 GB

    disk1s3 - Preboot [APFS Preboot]

        Filesystem: APFS

        Mount point: /System/Volumes/Preboot

        Used: 2.74 GB

        Shared values

            Size: 499.96 GB

            Free: 212.34 GB

    disk1s5 - VM [APFS VM]

        Filesystem: APFS

        Mount point: /System/Volumes/VM

        Used: 20 KB

        Shared values

            Size: 499.96 GB

            Free: 212.34 GB

    disk1s6 - Update

        Filesystem: APFS

        Mount point: /System/Volumes/Update

        Used: 6 MB

        Shared values

            Size: 499.96 GB

            Free: 212.34 GB

USB:

    USB 3.0 Bus

        USB-C multiport device

    USB 3.0 Bus

        <Empty>

    Apple T2 Bus

        Headset

        Apple T2 Controller

        FaceTime HD Camera (Built-in)

        Ambient Light Sensor

Network:

    Interface en0: Ethernet

    Interface bridge0: Thunderbolt Bridge

    Interface en1: Wi-Fi

        802.11 a/b/g/n/ac

    iCloud is limited without Full Disk Access

System Software:

    macOS Tahoe 26.2 (25C56)

    Installed 2026-01-18

    Time since boot: Less than an hour

Security:

    Gatekeeper: App Store and identified developers

    System Integrity Protection: Enabled

    Antivirus software: Apple

Unsigned Files:

    Apps: 3

System Launch Daemons:

    [Not Loaded] 43 Apple tasks

    [Loaded] 198 Apple tasks

    [Running] 180 Apple tasks

    [Other] 5 Apple tasks

Sorry about the 3 diff uploads, surprisingly, gemini.google AI told me that there is only 1,300 words so I kept cutting from bottom upwards....hence the 3 cut and paste. Sorry about that.

Here are TCP/IP, Proxies and Hardware settings. I think they are normal because I dont dabble in these and should be originals since inception.

The strange part is that , that only this imac is having issues but nothing else, and this is the only having Tahoe 26.2. So router is ok. iphone is ok, Catalina is ok.

Even the technician who came to replace the router (because of my complaints to the ISP) said the same thing, that there is something wrong with my software/hardware on the imac.

Any other things that you suggest I can do?

Or do you suggest I rollback the Tahoe 26.2?

Thanks a lot again,

[Edited by Moderator]