Very Slow speed on Wifi - Wrt1900AC V1

Hello All,
I am getting very slow wifi speed on Opewnrt with my Linksys WRT1900AC v1 model. This is on the OpenWrt 19.07.3 r11063-85e04e9f46. I have not made any changes on the config file. When i connect to the Linksys directly via lan, I get 98Mbps. On WIFI, I am getting 12-18Mbps. I am on a channel not used by anyone nearby. My wireless settings:

config wifi-device 'radio0'
	option type 'mac80211'
	option channel '11'
	option hwmode '11g'
	option path 'soc/soc:pcie@82000000/pci0000:00/0000:00:02.0/0000:02:00.0'
	option htmode 'HT20'
	option country 'DE'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option macaddr 'xxx.xxx.xxx'
	option key 'pass'
	option ssid 'IronHide'
	option encryption 'psk2'

config wifi-device 'radio1'
	option type 'mac80211'
	option channel '36'
	option hwmode '11a'
	option path 'soc/soc:pcie@82000000/pci0000:00/0000:00:03.0/0000:03:00.0'
	option htmode 'VHT80'
	option country 'DE'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option macaddr xxx.xxx.xxx
	option key 'pass'
	option ssid 'CyberTron'
	option encryption 'psk2'

Not sure, what could be wrong, but appreciate if you can point me to any config errors.

--Sachin

I installed the linksys firmware and got the 95Mbps, so seems like an issue with 19.0 version. On a plain 18.0 OOpenWRT version, i used to get the same speed. I am not sure what broke it. I went through some old forums but could not find anything significant.

Sachin