There were network outages after the AC power stop/resume at 3rd March. cal-gst1,2 could not reach DMG VPN network 192.168.30.x.
The reason was VLAN setting of DMG's network switch in KAGRA (SR-S352TR1) was lost.
So we set as that connection port #1 and #2 of cal-gst1,2 to same VLAN of DMG network "vlan untag 30" as below list, respectively.
Now the network connection is resumed.

Below is a part of setting table of SR-S352TR1 now.
ether 1 vlan untag 30
ether 1 description cal-gst1
ether 2 vlan untag 30
ether 2 description cal-gst2
...
ether 38 description hyades-0_irmc
ether 39 vlan untag 31
ether 39 description hyades-1_irmc
ether 40 vlan untag 31
ether 40 description kamups01
ether 49 vlan tag 30-31
ether 49 description kaml2sw02
ether 50 vlan untag 30
ether 50 description hyades-0
ether 51 vlan untag 30
ether 51 description hyades-1
ether 52 vlan untag 30
ether 52 description hyades-2

We also change the password of SR-S352TR1.