Re: Screen resolution can not be set higher than 1360x768 though Acer S243HL supports
And which messages can be found in that case in /var/log/Xorg.0.log ?
The only other hint to the problem in your provided Xorg.0.log file is that the driver can't read the EDID from your monitor. So it might be that the driver restricts itself to "safe" resolutions to avoid damaging the monitor because it doesn't know the monitors capabilities given usually by be EDID.
I would try two things in your case:
First try the latest driver version 260.19.29 to check if it still has the problem reading the EDID.
If this version still shows the problem I would start playing with a "custom EDID" . The "custom EDID" provides the monitors capabililties to the driver, just like a Windows "monitor driver" .inf file.