forum:
https://forum.dd-wrt.com/phpBB2/viewtopic.php?p=1270237#1270237

plugged into ports 1 or 2 you get a 192.168.1.x subnet ...handy for me sometimes
Also still have access to internet just fine connected to either port 1 OR 2 :-)

some pics of its config:










*****************************
mrjcd@daDeb:~$ ssh root@ea8500.mrjcd.com
DD-WRT v3.0-r49838 std (c) 2022 NewMedia-NET GmbH
Release: 08/23/22
Board: Linksys EA8500
==========================================================
 
     ___  ___     _      _____  ______       ____  ___ 
    / _ \/ _ \___| | /| / / _ \/_  __/ _  __|_  / / _ \
   / // / // /___/ |/ |/ / , _/ / /   | |/ //_ <_/ // /
  /____/____/    |__/|__/_/|_| /_/    |___/____(_)___/ 
                                                     
                       DD-WRT v3.0
                   https://www.dd-wrt.com


==========================================================


BusyBox v1.35.0 (2022-08-23 03:15:15 +07) built-in shell (ash)

root@EA8500:~# cat /proc/interrupts
           CPU0       CPU1       
 16:    7420573   12689677     GIC-0  18 Edge      gp_timer
 18:         65          0     GIC-0  51 Edge      qcom_rpm_ack
 19:          0          0     GIC-0  53 Edge      qcom_rpm_err
 20:          0          0     GIC-0  54 Edge      qcom_rpm_wakeup
 95:          0          0     GIC-0 241 Edge      ahci[29000000.sata]
 96:          0          0     GIC-0 210 Edge      tsens_interrupt
 97:         31          0     GIC-0  67 Edge      qcom-pcie-msi
 98:         30          0     GIC-0  89 Edge      qcom-pcie-msi
 99:          0          0     GIC-0 103 Edge      qcom-pcie-msi
100:     163489          0     GIC-0 202 Edge      adm_dma
101:      36207        918     GIC-0 255 Level     eth0
103:          0          0   PCI-MSI   0 Edge      aerdrv
104:         31          0   PCI-MSI   1 Edge      ath10k_pci
136:          0          0   PCI-MSI   0 Edge      aerdrv
137:         30          0   PCI-MSI   1 Edge      ath10k_pci
201:        249       1000     GIC-0 184 Level     msm_serial0
202:       1232        502     GIC-0 142 Level     xhci-hcd:usb1
203:        367        742     GIC-0 237 Level     xhci-hcd:usb3
IPI0:         0          0       CPU wakeup interrupts
IPI1:         0          0       Timer broadcast interrupts
IPI2:    234636     301336       Rescheduling interrupts
IPI3:      5566       7125       Function call interrupts
IPI4:         0          0       CPU stop interrupts
IPI5:    156890     157101       IRQ work interrupts
IPI6:         0          0       completion interrupts
Err:          0
root@EA8500:~#  nvram show | grep port *vlans
grep: *vlans: No such file or directory
root@EA8500:~#  nvram show | grep port. *vlans
grep: *vlans: No such file or directory
root@EA8500:~#  nvram show | grep port.*vlans
size: 39188 bytes (91884 left)
port6vlans=
port5vlans=1 2 16000
port4vlans=1
port3vlans=1
port2vlans=1
port1vlans=1
port0vlans=2
root@EA8500:~#  nvram show | grep vlan.*ports
size: 39188 bytes (91884 left)
vlan1ports=0 5
vlan0ports=1 2 3 4 5*
rc_startup=swconfig dev eth0 vlan 1 set ports "0t 3 4"
swconfig dev eth0 vlan 15 set ports "0t 1 2"
root@EA8500:~#  nvram show | grep vlan.*hwname
size: 39188 bytes (91884 left)
vlan0hwname=et0
vlan1hwname=et0
root@EA8500:~#  swconfig dev switch0 show
Global attributes:
	enable_vlan: 1
	enable_mirror_rx: 0
	enable_mirror_tx: 0
	mirror_monitor_port: 0
	mirror_source_port: 0
	disable_all_leds: ???
	arl_age_time: 300
	arl_table: address resolution table
Port 0: MAC c0:56:27:08:b2:92
Port 0: MAC 20:cf:30:9b:5a:89
Port 0: MAC 1a:0f:3a:9e:e0:6d
Port 0: MAC 00:0a:95:d5:61:80
Port 0: MAC 68:7f:74:15:70:25
Port 0: MAC 14:91:82:7d:ef:7d
Port 0: MAC 90:b1:1c:9c:f3:ef
Port 0: MAC ba:b8:9a:cf:34:be
Port 3: MAC 90:b1:1c:9c:f3:ef
Port 4: MAC ba:b8:9a:cf:34:be
Port 4: MAC 14:91:82:7d:ef:7d
Port 4: MAC 68:7f:74:15:70:25
Port 4: MAC 1a:0f:3a:9e:e0:6d
Port 4: MAC 20:cf:30:9b:5a:89
Port 4: MAC 00:0a:95:d5:61:80

	igmp_snooping: 0
	igmp_v3: 1
Port 0:
	mib: ???
	enable_eee: ???
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 0
	link: port:0 link:up speed:1000baseT full-duplex 
Port 1:
	mib: ???
	enable_eee: 0
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 15
	link: port:1 link:down
Port 2:
	mib: ???
	enable_eee: 0
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 15
	link: port:2 link:down
Port 3:
	mib: ???
	enable_eee: 0
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 1
	link: port:3 link:up speed:1000baseT full-duplex txflow rxflow auto
Port 4:
	mib: ???
	enable_eee: 0
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 1
	link: port:4 link:up speed:1000baseT full-duplex txflow rxflow auto
Port 5:
	mib: ???
	enable_eee: 0
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 2
	link: port:5 link:down
Port 6:
	mib: ???
	enable_eee: ???
	igmp_snooping: 0
	vlan_prio: 0
	pvid: 0
	link: port:6 link:up speed:1000baseT full-duplex 
VLAN 1:
	vid: 1
	ports: 0t 3 4 
VLAN 2:
	vid: 2
	ports: 0t 5 
VLAN 15:
	vid: 15
	ports: 0t 1 2 
root@EA8500:~# 
Connection to ea8500.mrjcd.com closed.
mrjcd@daDeb:~$ scp firmware.bin root@ea8500.mrjcd.com:/tmp
DD-WRT v3.0-r49838 std (c) 2022 NewMedia-NET GmbH
Release: 08/23/22
Board: Linksys EA8500
firmware.bin                                                                                            100%   23MB   1.2MB/s   00:19    
mrjcd@daDeb:~$ ssh root@ea8500.mrjcd.com
ssh: connect to host ea8500.mrjcd.com port 22: No route to host
mrjcd@daDeb:~$ date
Tue Aug 23 05:58:27 AM CDT 2022
mrjcd@daDeb:~$ 

 NO contact with router no how no way. Simple power cycle NO good :-(
Internet all good but NO contact with WNDR3700v4 which is plugged inti its WAN port :-|

3 button power switch trick brought it back to r49838 and all is good again  :-)