NUT客户端提示两台UPS服务器不可用的问题排查求助

大家好，我碰到了个棘手的问题，想请各位大佬帮忙看看。我的机柜里运行着两台NUT服务器：一台部署在TrueNAS SCALE（IP：10.27.0.61），另一台在Synology DS918+（IP：10.27.0.40），同时还有一台Ubuntu服务器作为NUT客户端。

最近这个Ubuntu客户端一直弹出广播警告，内容如下：

Broadcast message from nut@nuc13 (somewhere) (Sat Jan 27 16:16:52 2024):

UPS APC_ES850_G2@10.27.0.40 is unavailable

Broadcast message from nut@nuc13 (somewhere) (Sat Jan 27 16:16:52 2024):

UPS APC_ES850_G2_new@10.27.0.61 is unavailable

我已经把upsmon.conf里的注释都去掉了，内容如下：

MONITOR APC_ES850_G2@10.27.0.40 1 [username] [password] secondary

MONITOR APC_ES850_G2_new@10.27.0.61 0 [username] [password] secondary

MINSUPPLIES 1

SHUTDOWNCMD "/sbin/shutdown -h +0"

POLLFREQ 5

POLLFREQALERT 5

HOSTSYNC 15

DEADTIME 15

POWERDOWNFLAG /etc/killpower

RBWARNTIME 43200

NOCOMMWARNTIME 300

FINALDELAY 5

我尝试用telnet测试连接两台服务器，结果都正常：

连接Synology DS918+（IP认证，无需登录） #

$ telnet 10.27.0.40 3493

Trying 10.27.0.40...
Connected to 10.27.0.40.
Escape character is '^]'.

LIST UPS
BEGIN LIST UPS
UPS ups "Description unavailable"
END LIST UPS

LIST VAR ups
BEGIN LIST VAR ups
VAR ups battery.charge "100"
VAR ups battery.charge.low "10"
VAR ups battery.charge.warning "50"
VAR ups battery.date "2001/09/25"
VAR ups battery.mfr.date "2020/10/04"
VAR ups battery.runtime "1316"
VAR ups battery.runtime.low "120"
VAR ups battery.type "PbAc"
VAR ups battery.voltage "13.6"
VAR ups battery.voltage.nominal "12.0"
VAR ups device.mfr "American Power Conversion"
VAR ups device.model "Back-UPS ES 850G2"
VAR ups device.serial "5B2040T68465  "
VAR ups device.type "ups"
VAR ups driver.name "usbhid-ups"
VAR ups driver.parameter.pollfreq "30"
VAR ups driver.parameter.pollinterval "5"
VAR ups driver.parameter.port "auto"
VAR ups driver.parameter.synchronous "no"
VAR ups driver.version "DSM7-2-60108-221130"
VAR ups driver.version.data "APC HID 0.96"
VAR ups driver.version.internal "0.41"
VAR ups input.sensitivity "medium"
VAR ups input.transfer.high "266"
VAR ups input.transfer.low "180"
VAR ups input.voltage "241.0"
VAR ups input.voltage.nominal "230"
VAR ups ups.beeper.status "enabled"
VAR ups ups.delay.shutdown "20"
VAR ups ups.firmware "938.a2 .I"
VAR ups ups.firmware.aux "a"
VAR ups ups.load "22"
VAR ups ups.mfr "American Power Conversion"
VAR ups ups.mfr.date "2020/10/04"
VAR ups ups.model "Back-UPS ES 850G2"
VAR ups ups.productid "0002"
VAR ups ups.realpower.nominal "520"
VAR ups ups.serial "5B2040T68465  "
VAR ups ups.status "OL"
VAR ups ups.test.result "No test initiated"
VAR ups ups.timer.reboot "0"
VAR ups ups.timer.shutdown "-1"
VAR ups ups.vendorid "051d"
END LIST VAR ups

^]
telnet> quit
Connection closed.

连接TrueNAS SCALE（需用户名密码登录） #

$ telnet 10.27.0.61 3493

Trying 10.27.0.61...
Connected to 10.27.0.61.
Escape character is '^]'.

USERNAME [username]
OK
PASSWORD [password]
OK

LIST UPS
BEGIN LIST UPS
UPS APC_ES850_G2-new "APC Back-UPS ES850 G2 new"
END LIST UPS

LIST VAR APC_ES850_G2-new
BEGIN LIST VAR APC_ES850_G2-new
VAR APC_ES850_G2-new battery.charge "100"
VAR APC_ES850_G2-new battery.charge.low "10"
VAR APC_ES850_G2-new battery.charge.warning "50"
VAR APC_ES850_G2-new battery.date "2001/09/25"
VAR APC_ES850_G2-new battery.mfr.date "2023/06/19"
VAR APC_ES850_G2-new battery.runtime "1228"
VAR APC_ES850_G2-new battery.runtime.low "120"
VAR APC_ES850_G2-new battery.type "PbAc"
VAR APC_ES850_G2-new battery.voltage "13.5"
VAR APC_ES850_G2-new battery.voltage.nominal "12.0"
VAR APC_ES850_G2-new device.mfr "American Power Conversion"
VAR APC_ES850_G2-new device.model "Back-UPS ES 850G2"
VAR APC_ES850_G2-new device.serial "5B2325T40076  "
VAR APC_ES850_G2-new device.type "ups"
VAR APC_ES850_G2-new driver.name "usbhid-ups"
VAR APC_ES850_G2-new driver.parameter.pollfreq "30"
VAR APC_ES850_G2-new driver.parameter.pollinterval "2"
VAR APC_ES850_G2-new driver.parameter.port "auto"
VAR APC_ES850_G2-new driver.parameter.synchronous "auto"
VAR APC_ES850_G2-new driver.version "2.8.0"
VAR APC_ES850_G2-new driver.version.data "APC HID 0.98"
VAR APC_ES850_G2-new driver.version.internal "0.47"
VAR APC_ES850_G2-new driver.version.usb "libusb-1.0.26 (API: 0x1000109)"
VAR APC_ES850_G2-new input.sensitivity "medium"
VAR APC_ES850_G2-new input.transfer.high "266"
VAR APC_ES850_G2-new input.transfer.low "180"
VAR APC_ES850_G2-new input.voltage "242.0"
VAR APC_ES850_G2-new input.voltage.nominal "230"
VAR APC_ES850_G2-new ups.beeper.status "enabled"
VAR APC_ES850_G2-new ups.delay.shutdown "20"
VAR APC_ES850_G2-new ups.firmware "938.a2 .I USB "
VAR APC_ES850_G2-new ups.load "28"
VAR APC_ES850_G2-new ups.mfr "American Power Conversion"
VAR APC_ES850_G2-new ups.mfr.date "2023/06/19"
VAR APC_ES850_G2-new ups.model "Back-UPS ES 850G2"
VAR APC_ES850_G2-new ups.productid "0002"
VAR APC_ES850_G2-new ups.realpower.nominal "520"
VAR APC_ES850_G2-new ups.serial "5B2325T40076  "
VAR APC_ES850_G2-new ups.status "OL"
VAR APC_ES850_G2-new ups.test.result "No test initiated"
VAR APC_ES850_G2-new ups.timer.reboot "0"
VAR APC_ES850_G2-new ups.timer.shutdown "-1"
VAR APC_ES850_G2-new ups.vendorid "051d"
END LIST VAR APC_ES850_G2-new

^]
telnet> quit
Connection closed.

明明telnet连接都正常，能获取到UPS的状态，但客户端就是提示不可用，有没有朋友知道哪里出问题了？麻烦指点一下，谢谢！

备注：内容来源于stack exchange，提问作者crackpot