SOPHOS loses wan

Hi!

I have Sophos XG106 rev.1 with home license activated SFVH (SFOS 19.5.1 MR-1-Build278) . 

Every few days the gateway/wan port goes down, attached log bellow:

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cd /log
tail -f dgd.log

NOTICE Mar 17 09:45:33Z [5495]: Executing : <gateway:gw_dead_to_live> args : <{ "param": "@Internet", "targets": [ ] }>
WARNING Mar 24 23:08:07Z [5495]: Actiontree, Live to Dead
NOTICE Mar 24 23:08:07Z [5495]: Executing : <gateway:gw_live_to_dead> args : <{ "param": "@Internet", "targets": [ { "proto": "PING", "ip": "192.168.100.1", "port": 0 }, { "proto": "TCP", "ip": "216.58.210.131", "port": 443 } ] }>
MESSAGE Mar 25 10:35:18Z [5502]: ****************************************
MESSAGE Mar 25 10:35:18Z [5502]: Starting DGD: Sat Mar 25 12:35:18 2023
MESSAGE Mar 25 10:35:18Z [5502]: ****************************************
NOTICE Mar 25 10:35:41Z [5502]: Main, entities count: 1 rule_count:2

NOTICE Mar 25 10:35:41Z [5502]: Executing : <gateway:gw_dead_to_live> args : <{ "param": "@Internet", "targets": [ ] }>

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I have my sophos fw behind ISP-modem/router, 192.168.100.1 is my modem ip and it is IP passthrough mode.

I have tried everything but still no clue why my port1=WAN goes down.

Previously the firewall worked for 8 days without failure then gateway is down and internet.

My modem is not the problem I have tested connectivity when sophos fw gateway is down. Boot restores connection in sophos fw.

Could anybody help me?? Please!