5490 AIO used as external monitor resolution limited to 1360 x 768

If your 5490 AIO could display FHD, 1920x1080 with itself and with certain device, the fault is with the devices that output the video signals or the connecting cables.  Test with high quality HDMI cable.  

5450 seems to be an old latitude model with intel 4th/5th gen cpu.  what is the model number of your spouse's latitude?

is the native display HD or FHD? 

https://www.dell.com/support/manuals/en-us/latitude-e5450-laptop/dell_latitude_e5450_om-v1/technical-specifications?guid=guid-ff58d80e-59c8-4c89-bcf1-57aedc89cc0d&lang=en-us

Sorry, i messed up on the model numbers ...

Her laptop is 

• Latitude 5440
• 13th Gen Intel Core i7-1365U v Pro
• 14.0" FHD (1920x1080) Non-Touch

My laptop is

• Latitude 5430
• 14.0" FHD (1920x1080) Anti Gla re, SLP, Non-Touch
• i7-1265U vPro

Our home laptop is:

• Inspiron 5406 2-in-1
• I7-1165G7
• ASSY,LCD,14.0,FHD,TSP,TPK,AUO

can you check dev mgr of your 5440 or 5430 look under display adapter?  Is there a Intel Xe graphics adapter properly installed?

5440:

did you use the same HDMI cable to check non-Dell laptop (like ur son's chromebook) and get 1080p?

@redxps630​ Yes, the 5440, 5430 and 5406 show "Intel Iris Xe Graphics" installed and functioning properly under the Display Adapters.

• 5440 - 2/21/2024 31.0.101.5333
• 5430 - 11/7/2023 31.0.101.4953
• 5406 - 1/18/2024 31.0.101.5186

Tried multiple cables and all failed with the dell laptops.  I used a playstation 5 cable for when i was checking the chromebook (that worked at 1920x1080); same cable was limited to 1360x768 when connected to the dell laptops.

If you had a standard stand alone 1080p/1440p monitor you could test the Latitude HDMI-OUT port by connecting it to the Latitude.

There is one user reported "solution" which is to use a USB C to HDMI converter than the native HDMI out port of laptop.  Latitude Thunderbolt 4 to the converter, converter HDMI to 5490 AIO.  credit to chino.

Thunderbolt 4.0 with DisplayPort Alt Mode/USB Type-C/USB4/Power Delivery

Supports USB4, DisplayPort 1.4, Thunderbolt 4 and also enables you to connect to an external display using a display adapter. Provides data transfer rates of up to 40 Gbps for USB4 and  

https://www.dell.com/community/en/conversations/inspiron-desktops/inspiron-5490-aio-hdmi-in-resolution/65e518a562484464eb62ccc4

@redxps630​ All the laptops work fine with our (3) other 1920x1080 monitors.  It is only when it is connected to the Inspiron 5490 AIO that the display incorrectly limits to 1360x768.  When using a docking station for a 2 monitor setup the other monitor correctly detects 1920x1080 but the AIO monitor is still 1360x768.

I did the workaround in the other post you mentioned with the Belkin adapter version that was mentioned in a reply (Belkin USB C to HDMI Adapter + USBC Charging Port to Charge While You Display, Supports 4K UHD Video, Passthrough Power up to 60W for Connected Devices, Compatible with MacBook, iPad, Windows) a few weeks ago but it didn't work either.

I've tried connecting it directly to the laptop as well as through Dell Docking Stations (both usb c and thunderbolt versions) and a Targus port replicator ... they are failed as well.

so I tested my Inspiron 24 5400 AIO using an old Del Latitude E7250.

I got the same 1080p on the AIO as the E7250 native display which is also 1080p.

you can try update the bios of your AIO.  I am not sure why your latitude is not able to produce 1080p on your 5490 AIO.

I have the same problem with Dell XPS 14 9440 laptop and Dell Inspiron 2350. Maximum resolution that is available is 1360x768. I tried two different type c HDMI adapters (including one that is coming with XPS laptop), I tried two different HDMI cables. Also when I use same cables and same type c hubs with HDMI output on XPS 15 9575 - 1920x1080 FHD can be set when connecting to this AIO Inspiron. I tried both latest Intel video drivers and latest video drivers from Dell. And I have Intel Arc integrated graghics card on XPS that fails to detect correct resolutions. Did you get any success or maybe have other ideas to get it working in FHD ?

I have found a solution for my Inspiron 2350 AIO and XPS 14 with RCU utility (https://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU?page=1) that allows to configure resolutions and timings for HDMI profiles. In my case I have noticed that 1920x1080 is present but has 60Hz. The nearby 1360x768 resolution has 60,016 Hz. I have changed 1920's clock value to  60,016, restarted driver and more resolutions appeared in system for AIO including 1920x1080 that is working now. Hope it will help in your case too.