ASUS AC88U: What 5 GHz channels are available?

Hello, I'm having trouble configuring my AC88U. It's not clear to me what 5 GHz channels and channel widths are available, since using combinations that would normally work with the retail firmware makes wireless in the 5 GHz band unavailable, usually until I restart the router.

For example I just changed to channel 52 with a width of 80 MHz and the log says senseless stuff like:

Thu Apr  6 11:56:18 2023 kern.err kernel: [   71.951517] ieee80211 phy1: brcmf_cfg80211_start_ap: Set Channel failed: chspec=57466, -52
Thu Apr  6 11:56:24 2023 kern.err kernel: [   77.963256] ieee80211 phy1: brcmf_cfg80211_start_ap: Set Channel failed: chspec=57466, -52
Thu Apr  6 11:56:30 2023 kern.err kernel: [   83.975080] ieee80211 phy1: brcmf_cfg80211_start_ap: Set Channel failed: chspec=57466, -52
Thu Apr  6 11:56:36 2023 kern.err kernel: [   89.989280] ieee80211 phy1: brcmf_cfg80211_start_ap: Set Channel failed: chspec=57466, -52
Thu Apr  6 11:56:42 2023 kern.err kernel: [   96.002543] ieee80211 phy1: brcmf_cfg80211_start_ap: Set Channel failed: chspec=57466, -52
Thu Apr  6 11:56:45 2023 daemon.notice hostapd: Remove interface 'wlan1'
Thu Apr  6 11:56:45 2023 daemon.notice hostapd: wlan1: interface state HT_SCAN->DISABLED
Thu Apr  6 11:56:45 2023 daemon.notice hostapd: wlan1-1: AP-DISABLED
Thu Apr  6 11:56:45 2023 daemon.notice hostapd: wlan1-1: CTRL-EVENT-TERMINATING
Thu Apr  6 11:56:45 2023 daemon.err hostapd: rmdir[ctrl_interface=/var/run/hostapd]: Permission denied
Thu Apr  6 11:56:46 2023 daemon.notice netifd: Network device 'wlan1-1' link is down
Thu Apr  6 11:56:46 2023 kern.info kernel: [  100.186467] br-lan: port 9(wlan1-1) entered disabled state
Thu Apr  6 11:56:46 2023 kern.err kernel: [  100.195814] ieee80211 phy1: brcmf_cfg80211_get_channel: chanspec failed (-52)
Thu Apr  6 11:56:46 2023 kern.info kernel: [  100.204012] device wlan1-1 left promiscuous mode
Thu Apr  6 11:56:46 2023 kern.info kernel: [  100.208855] br-lan: port 9(wlan1-1) entered disabled state
Thu Apr  6 11:56:46 2023 daemon.notice hostapd: nl80211: Failed to remove interface wlan1-1 from bridge br-lan: No such device
Thu Apr  6 11:56:46 2023 daemon.notice hostapd: wlan1: AP-DISABLED
Thu Apr  6 11:56:46 2023 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Thu Apr  6 11:56:46 2023 daemon.err hostapd: rmdir[ctrl_interface=/var/run/hostapd]: Permission denied
Thu Apr  6 11:56:46 2023 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Thu Apr  6 11:56:46 2023 kern.info kernel: [  100.326435] device wlan1 left promiscuous mode
Thu Apr  6 11:56:46 2023 kern.info kernel: [  100.330974] br-lan: port 7(wlan1) entered disabled state
Thu Apr  6 11:56:47 2023 daemon.notice netifd: radio1 (3372): command failed: No error information (-524)
Thu Apr  6 11:56:47 2023 daemon.notice netifd: Wireless device 'radio1' is now down
Thu Apr  6 11:56:47 2023 daemon.notice netifd: radio1 (3398): command failed: No error information (-524)
Thu Apr  6 11:56:47 2023 daemon.notice netifd: radio1 (3398): command failed: I/O error (-5)
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: Configuration file: /var/run/hostapd-phy1.conf (phy wlan1) --> new PHY
Thu Apr  6 11:56:49 2023 kern.info kernel: [  102.474785] br-lan: port 7(wlan1) entered blocking state
Thu Apr  6 11:56:49 2023 kern.info kernel: [  102.480315] br-lan: port 7(wlan1) entered disabled state
Thu Apr  6 11:56:49 2023 kern.info kernel: [  102.485841] device wlan1 entered promiscuous mode
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: wlan1: interface state UNINITIALIZED->COUNTRY_UPDATE
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: wlan1: interface state COUNTRY_UPDATE->HT_SCAN
Thu Apr  6 11:56:49 2023 kern.err kernel: [  102.493707] ieee80211 phy1: brcmf_run_escan: error (-52)
Thu Apr  6 11:56:49 2023 kern.err kernel: [  102.499098] ieee80211 phy1: brcmf_cfg80211_scan: scan error (-52)
Thu Apr  6 11:56:49 2023 kern.info kernel: [  103.026355] br-lan: port 7(wlan1) entered disabled state
Thu Apr  6 11:56:49 2023 kern.info kernel: [  103.033513] device wlan1 left promiscuous mode
Thu Apr  6 11:56:49 2023 kern.info kernel: [  103.038230] br-lan: port 7(wlan1) entered disabled state
Thu Apr  6 11:56:49 2023 kern.err kernel: [  103.088825] ieee80211 phy1: brcmf_run_escan: error (-52)
Thu Apr  6 11:56:49 2023 kern.err kernel: [  103.094210] ieee80211 phy1: brcmf_cfg80211_scan: scan error (-52)
Thu Apr  6 11:56:49 2023 daemon.err hostapd: Failed to request a scan of neighboring BSSes ret=-52 (No error information)
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: wlan1: interface state HT_SCAN->DISABLED
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: wlan1: AP-DISABLED
Thu Apr  6 11:56:49 2023 daemon.err hostapd: wlan1: Unable to setup interface.
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: nl80211: deinit ifname=wlan1 disabled_11b_rates=0
Thu Apr  6 11:56:49 2023 daemon.notice hostapd: nl80211: Failed to remove interface wlan1 from bridge br-lan: Invalid argument
Thu Apr  6 11:56:50 2023 daemon.err hostapd: rmdir[ctrl_interface=/var/run/hostapd]: Permission denied
Thu Apr  6 11:56:50 2023 daemon.notice hostapd: wlan1: CTRL-EVENT-TERMINATING
Thu Apr  6 11:56:50 2023 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1 wasn't started
Thu Apr  6 11:56:50 2023 daemon.err hostapd: rmdir[ctrl_interface=/var/run/hostapd]: Permission denied
Thu Apr  6 11:56:50 2023 daemon.notice hostapd: wlan1-1: CTRL-EVENT-TERMINATING
Thu Apr  6 11:56:50 2023 daemon.err hostapd: hostapd_free_hapd_data: Interface wlan1-1 wasn't started
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): Command failed: ubus call hostapd config_add {"iface":"wlan1", "config":"/var/run/hostapd-phy1.conf"} (Invalid argument)
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): Usage: ubus [<options>] <command> [arguments...]
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): Options:
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -s <socket>:		Set the unix domain socket to connect to
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -t <timeout>:		Set the timeout (in seconds) for a command to complete
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -S:			Use simplified output (for scripts)
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -v:			More verbose output
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -m <type>:		(for monitor): include a specific message type
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): 			(can be used more than once)
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  -M <r|t>		(for monitor): only capture received or transmitted traffic
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): Commands:
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - list [<path>]			List objects
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - call <path> <method> [<message>]	Call an object method
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - subscribe <path> [<path>...]	Subscribe to object(s) notifications
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - listen [<path>...]			Listen for events
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - send <type> [<message>]		Send an event
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - wait_for <object> [<object>...]	Wait for multiple objects to appear on ubus
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):  - monitor				Monitor ubus traffic
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398):
Thu Apr  6 11:56:50 2023 daemon.notice netifd: radio1 (3398): Device setup failed: HOSTAPD_START_FAILED
Thu Apr  6 11:56:50 2023 daemon.notice netifd: Wireless device 'radio1' set retry=0
Thu Apr  6 11:56:50 2023 daemon.crit netifd: Wireless device 'radio1' setup failed, retry=0
Thu Apr  6 11:56:50 2023 daemon.notice netifd: Wireless device 'radio1' is now down

I am trying to change the channel because I have weird problems with jitter that do not occur with the retail firmware.

I have the suspicion that the wireless firmware is simply buggy in this regard but I'm not sure if I'm doing something wrong.

No channel other than 36 work for me.
The WiFi power is lower too. My link speed never exceeds 340 on 2x2 when it used to be 585/680.