19.07.03 renewing WAN IP every hour

I've been looking in my logs trying to figure out why my business Skype calls occasionally drop. I don't know if this is related but I noticed that my WAN is renewing every hour. Is this normal?

Wed Jun  3 10:53:58 2020 daemon.notice netifd: wan (1923): udhcpc: sending renew to 74.96.XYZ.1
Wed Jun  3 10:53:58 2020 daemon.notice netifd: wan (1923): udhcpc: lease of 74.96.XYZ.181 obtained, lease time 7200
Wed Jun  3 11:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: sending renew to 74.96.XYZ.1
Wed Jun  3 11:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: lease of 74.96.XYZ.181 obtained, lease time 7200
Wed Jun  3 12:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: sending renew to 74.96.XYZ.1
Wed Jun  3 12:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: lease of 74.96.XYZ.181 obtained, lease time 7200
Wed Jun  3 13:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: sending renew to 74.96.XYZ.1
Wed Jun  3 13:53:59 2020 daemon.notice netifd: wan (1923): udhcpc: lease of 74.96.XYZ.181 obtained, lease time 7200

Yes, this is normal, because your lease time is 7200 seconds = 2 hours. The first renew is done after half of your lease time = 1 hour.

I don't know, whether it is related to your skype call drops. I suppose it is not, but perhaps somebody else can jump in.

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That will not cause a gap in connectivity though since it renews to the same IP.

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Is a 2 hour lease time typical? I was looking for where the lease time might be set and couldn't find it. Is this driven from my ISP?

Yes, you do not have the ability to control this lease time (on the ISP side).

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Not always...my IP didn't change but I get a firewall trigger but only at that particular moment but periodic every day. All the times earlier or later it will not happen. Probably this could cause issues at least in my case.

Wed Jun 3 07:48:02 2020 daemon.notice netifd: wan (1856): udhcpc: sending renew to 10....
Wed Jun 3 07:49:54 2020 daemon.notice netifd: wan (1856): udhcpc: sending renew to 10....
Wed Jun 3 07:50:50 2020 daemon.notice netifd: wan (1856): udhcpc: sending renew to 0.0.0.0
Wed Jun 3 07:50:51 2020 daemon.notice netifd: wan (1856): udhcpc: lease of 176.... obtained, lease time 7200
Wed Jun 3 07:50:51 2020 user.notice firewall: Reloading firewall due to ifupdate of wan (eth0.2)

It depends on ... I have routers, where the dhcp server grants lease time from 2 hours until infinite.

The lease time is a configuration value of the dhcp server (e.g. in openwrt look at Interfaces->DHCP-Server->General-Setup). If you don't have access to the dhcp server (e.g. if it is located at your ISP), you have no influence on the lease time.

On the dhcp client side you have only limited influence on the lease time. udhcpc (the dhcp client software with openwrt) knows the option

-x lease:3600

With this option you express your request of a lease time of 3600 seconds. It's a matter of the dhcp server to fullfill or deny your request.

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