In this article, we explained how to manually change Holdtime & Keep alive intervalfor for individual BGP neighbors. By default, all BGP configuration inherits the default Hold & Keep alive timers if they are not manually configured.
By default, the Hold Timer is 90 seconds & Keep Alive timer is 30 seconds.
In this scenario, we already configure basic BGP between SonicWall and the ISPs router using CLI(Command Line Interface) to advertise our network (with a public IP address) to the ISP. It is necessary to have the AS(Autonomous System) numbers and public IP addresses of both devices. This information should be provided by ISP.

To know how we configured BGP, please refer How can I configure BGP (Border Gateway Protocol) with single ISP and advertise your public network?
Please refer below command to change the timers.
Syntax: neighbor <public IP of neighborr> timers <Keepalive value> <Holdtime value>
Values as below
<0-65535> Keepalive interval connect BGP connect timer
<0-65535> Holdtime
EXAMPLE: neighbor 1.1.1.1 timers 90 180 90 is Keepalive & 180 is Holdtime.
In this article, we explained the procedure to change the Hold time to 180 seconds & Keep alive interval to 60 seconds.
conf troutingbgpconf trouter bgp 100neighbor 1.1.1.1 timers 60 180endwrite